External SSD Recommendation for new iMac

Instead of booting off the external, why not configure the iMac with a 256GB SSD for applications and booting. Your data (or a good bit of it) could be stored on an external. Depending on what your tasks are, a 256GB drive should be sufficient to keep a significant amount of data on with an external storing the overflow. Unless you are doing something where data access needs to be incredibly fast this would have the advantage of allowing you to use a lower cost USB 3 enclosure instead of a thunderbolt enclosure.

The savings would be significant. By the time you've purchased a quality Thunderbolt enclosure, cable, and SSD you'll have already spent enough to purchase the 500GB SSD upgrade for the iMac. My suggestion will save you several hundred dollars.

Which one are you referring to? I have several of the Mercury Pro Minis (which have SSD options) and have a power adapter (which you can buy separately) - here is the back of the Mini showing the DC in:

You could check this source - they have a good customer service dept and you should be able to get an answer there:

https://www.macsales.com/

(that is where I get most of my stuff from - they are Mac centric and actually test their stuff)

Personally I think I'd spend the money on an internal 500GB SSD or 1T SSD and use it as my startup disk.

Why, because confusion say's......

Always boot from the fastest most reliable drive and use those less reliable plug-in drives for backups.

Seems like a waste to have an HDD or Fusion Drive and then not like or use it.

APFS busted a sweet RAID 1 of 480GB SSDs in one of my Mac Mini.

So now, I run from one 480GB and clone to the other.

you said "I would like to keep the performance of the Mac similar to what an internal SSD "

I say "no way." Unless you spend a lot of bucks and it is not worth it.

I would also say if you are buying new, get it with an internal. SSD.

Personally, I would spend the extra $100 for a 256GB and just go

with system and apps on it and use external drives (SSD or HDD)

for all else. Music and even videos will play just fine with USB3

and you really don't need much faster unless unless you are doing

high-end uncompressed video work.