External SSD for iMac?

I have a 27" 2017 iMac that came with a 1 TB Fusion drive. I'm not really unhappy with it, but have been exploring SSD options. I've found that I can't just put a regular SSD into it, I have to have use Flash memory, and I have to buy it from the company that does the install.

I have read that people are using external SSD's with a thunderbolt connection as a boot drive. Has anyone tried this, and if so, are you happy with it?

I'm not worried about startup because I never turn it off. I am most interested in seeing if I can get a noticeable improvement in LR and PS.

Thanks in advance!

Talk to Other World Computing (aka OWC. eshop.macsales.com). They've been Mac specialists for decades. They have a lot of external SSD options that are compatible with your iMac. I'm eyeing the Mercury Elite Pro Dual Mini enclosure with one bay containing a Samsung EVO 850 SSD for the files I'm working on at the time (last couple of shoots) and the other bay with a 2TB or 4TB HDD for cheaper long term storage of the entire archive.

What don't you like with the fusion drive? If you're finding PS and LR being slow, are you sure it's the HD? A fusion drive is a hybrid drive, and the OS puts frequently used apps on its SSD. The only time it may run slower (due to hard drive), is if the application sizes exceed the SSD size in the fusion drive. It is a standard 2.5 laptop HD that you can upgrade in an iMac, but it's recommended to use a repair company so you can keep your warranty. To try to upgrade it yourself, you'd have to remove the display and get at the drive bay that's under the display panel:

This is specifically the 21.5" model, but 27" would be the same:
How to Upgrade the Main Drive in a 21.5-inch iMac 2017

As for external drives, I think SSD is overkill right now. The bus speeds just aren't there....the 7200 rpm drives are the best price/performance for storing data (videos or photos).

Thanks for the info. I'm not unhappy with the speeds, I'm just putting together a wish list and was thinking of switching to an SSD. There is a company here in Indianapolis, The Mac Experience. They charge $165 to upgrade the hard drive in my iMac, I would NEVER attempt to do it myself. I took my 2011 MBP apart, but this iMac cost too much for me to play with! I'm going to check out the enclosure that williaty mentioned.

Been booting and operating from a SanDisk 500GB Extreme 500 Portable SSD for a little over 2 years on a late 2013 27" iMac. Have had literally zero issues. You can velcro to the back of your imac and never see it again ... it's tiny and weighs ounces. Not going to debate speeds etc ... Suffice to say it's USB3 and far exceeds any spinner and relocation ( physical ) / updates and backups are stupid simple. And if you want you can partition the internal to use as backup / storage.

That sounds great, exactly what I was looking for! Thank you!