Q: El Capitan or Mavericks?

If the computer shipped with Mavericks, you may be able to re-install the original OS X version

and its applications from the App Store; it would be downloaded & take time...

Given adequate free or unused hard drive capacity, you would have other options to restore

and use the older OS X without erasing the newer one.

An idea would be, if you can restore the older OS X, have a partition for it, and be able to boot

the newer OS X and older one from the same computer. Some users chose to install the new

system on a separate partition so as to keep older applications in their native environs and be

able to run them without chance of unsupported third-party apps, or without buying new versions.

There would be nothing untoward about restoring to an older OS X - if the computer shipped with it.

Otherwise, you cannot download the Mavericks from the Mac App Store because it's not there...

In any event, good luck in this matter!

you could backup, split the drive into two partitions and boot to either 10.9 or 10.11 provided you have installers for both on some bootable media, then restore your data.

if you're not running into issues and your software needs don't seem to be incompatible with 10.11 and the UI is the only issue I don't think you'll see much of a difference in performance on 10.9 and 10.11. I'm using a 2010 Mac Pro for mostly 3D and Creative Cloud work and haven't noticed one OS is any slower than the other at this time.

it all seems to be the same between mavericks and El Capitan but my system while being old is still essentially a halfway decent workstation (dual quad core xeon and 64 GB RAM) except when I'm using Adobe Creative Cloud 2015 and it hesitates when I use the menus. I didn't have Cloud on Mavericks so I can't compare.  If you're using older software that works you may wish to say on 10.9 or backup everything before updating to make sure you can still work. El Cap is smoother for me than Yosemite but Yosemite was clunkier than Mavericks for me so it's about even. Most of what I do when I'm not tech support is 3D design and my antiquated ATI card is still good and my CPU's get a workout so my experience has been good. I did run into issues with some music software, and I looked at the company page for answers and they had posted 10.11 broke some of the functionality, they were asking Apple for help with 10.11.1 and then updated that to say it sort of works but they were not satisfied. What does that mean? I think it means Apple did make changes that Developers were trying to fix on their end but couldn't quite get it in time or Apple changed something that's really got some developers baffled as we saw with MS 2016.

If it ain't broke don't fix it is what we say over here. Mavericks is one of the more stable OS X flavors but there will be no more updates for it, it's a finished product. El Capitan is still new, there is likely a public 10.11.2 soon so it could get better or worse.

What are the benefits of each and what are the caveats? Make a list and see which side is longer - and while you do that backup anyway!

if you have the funds RAM is relatively inexpensive. If your mac can be upgraded you would likely get improvement from adding more RAM. The limits are with the model and year and it would benefit you in any OS you decide to go with.

The model MacBook Pro7.1  (13-inch?) circa 2010 model would have shipped with a version

of OS X 10.6.3 or 10.6.4 on original DVD media specific to that computer, when new...

{Usually when resold, the unit should be reverted back to this OS X & that DVD included.}

If your model MacBook Pro6.2 is a 15-inch and not the 13-inch display, the total memory or

RAM upgrade would be limited to 8GB, or two 4-GB chips of the same spec listed below.

So, Memory or RAM specifications suggest the aftermarket total upgrade capacity in 13-

inch model can be 16GB, when both slots on the logic board see equal 8GB chips. In this

model, not in the 15-inch, the standard RAM is shared with graphics; in the 15-inch model

the computer uses a different graphic processor. See specs based on your build model.

According to MacTracker database (available as free app from http://mactracker.ca) the model

7.1 MB/Pro shares the RAM with the graphic chip, so an upgrade would allow more RAM to be

available to run graphics as needed. The specification for the RAM or memory, is:

Maximum Memory    16 GB (2.4 GHz Actual) 8 GB (Apple)

Memory Slots    2 - 204-pin PC3-8500 (1066 MHz) DDR3 SO-DIMM

• MacBook Pro 13" Mid 2010 - View Memory Options - OWC macsales

This company also offers other replacement parts, upgrade SSD & etc.

• MacBook Pro: How to remove or install memory -- Apple Support

My experience with Mavericks 10.9(.5) is limited to the past 10 months or so, and not full

time; the computer I bought included 10.9 as it shipped from Apple with Mavericks yet

since it was new-old-stock, nobody could tell me prior to purchase which OS X was inside.

Once bought, I had access to the serial number and did some research by serial # lookup.

My other, older Macs mostly use Leopard OS X 10.5.8, one is a first model MacBook 1.83GHz

coreduo 13-inch; it could use Snow Leopard OS X 10.6.8 if purchased. The others are G4 PPC

models from before 2006, and their upper limit in OS X is set by their architecture and age. In

many ways, Snow Leopard is a great system to leave a vintage early Intel-mac, as standalone.

{This model bought could have had one of three different OS X, based on build year model.

My choice in computer was based on the ability to upgrade the physical memory chips and

also the hard disk drive, the clock battery and some other basic features, as a last model

in the series which allowed memory chips to be replaced by the user. Mavericks is OK but

this and later OS X versions prefer more RAM; when it cannot be supplied, a fast upgrade

option would be to upgrade to an SSD and move away from slower rotational hard drives.}

Hopefully your experience will be good and if you save an installer for Mavericks, it may be

used to re-install to the computer or a separate partition. Otherwise, you would be unable to

buy or re-download from the Mac App Store because Mavericks is no longer available. And

usually an upgrade to a later OS X relates your Apple ID to the App Store and the system's

future access to software upgrade/update. If you were able to personalize the OS X 10.9

installation, there would be less issue in re-installing it from your Purchases in App Store.

However, some have tried to re-install after an upgrade to find it difficult or impossible later.

In any event...

Good luck & happy computing!