To All those that have either a pro or air or have had both, would you rather have a I5 16g of ram Pro or an I7 4g of Ram Pro, with speed being the primary concern

The i7 would make much better use of the memory because of the quadcore hyperthreading. Either way for me it would have to have a 256 SSD @6G

Looks like 4GB is the max available from Apple and unless they have changed things a lot the RMA is NOT upgradeable, it's hardwired (soldered) into the motherboard.

As RRFS said, the Air maxes out at 4GB RAM.

In the course of about a year I upgrade my 13" MBP with 4GB RAM to 8GB RAM (a mechanical drive) then I replaced that drive with an SSD. Amazing difference. Then over the holidays my wife gave me a MBA (13" 4G RAM). When I upgraded from 4 to 8GB on the MBP I really needed the extra RAM, I'd begun to see beach balls regularly after upgrading Office 2011. Of course adding the SSD was a huge revelation - made me wish I'd done it sooner.

But the real kicker is comparing the 4GB MBA and the 4GB MBP with a mechanical drive. I'm using the same software on the Air as I did on the MBP and I never see a beach ball. The SSD makes virtual memory almost transparent. I never had the chance to try it but I wonder if the MBP line (as it exists today) uses the SSD as effectively as the Air does.

Are your processors similar? Did you upgrade the MBP with a SSD that runs at the same speed as the Pro? I've seen them at 1.5GBs 3.0GBs 6GBs. My iMac is a 2008 so anything over 1.5GBs wuold have been too fast but matching i/o speed would probably enhance performance.

I can add as well that I've found the SSD to be the big difference. I too upgraded a MacBook Pro (late 2008) from 4GB to 8GB because I was seeing beach balls due to RAM filling up while running a number of programs. I was somewhat leery of the Air and the 4GB limit due to that experience.

I originally picked up an 11" Air for a "backup" machine (I do presentations on the road and the Air gave me a "safety net" if the main machine died) and for working with on planes (the 15" MBP is too big to comfortably work with in coach, especially if the person in front of me reclines). However I noticed that I could load exactly the same programs that had brought the MBP to "beach ball" mode with 4GB on the Air and never miss a beat.

In fact, the 4GB Air feels faster overall than the 8GB MBP, primarily due to the fast booting. While beach balls would come up from time to time, starting programs happens more regularly. And since the SSD makes swapping less time consuming, there's not as much penalty if it does swap and there' s a huge plus for starting programs.

I certainly can see a use case where the RAM would make a difference (and thus make the 8GB MBP faster), even with the SSD on the Air, but it certainly isn't what I do regularly, nor do I think it's what most users are doing regularly.

That is, the key thing to figure out is whether your use currently is speed limited by disk access, processor speed or RAM on your current equipment. Given the relative slowness of mechanical drives compared to other things a computer can do, any signfiicant use of the disk tends to make that speed the limiting factor.

I advise that you get the standard RAM with the Pro. macsales.com and crucial.com sell RAM for about 25% of Apple's "at time of sale" price ... 8 GB can be had for about $50. 16 GB RAM at macsales.com is going for $187.