I am one of the fitech suckers. It's been great for me. Cranked up the first time I bolted it on. I'm also running an in-line pump, and haven't had an issue.
But because of no issues (I mean beyond basic tuning) I've never reached out to Fi-tech for support. My guess, from joining a fi-tech group on facebook, is for tech support, they seem pretty available, but if you are trying to return or get warranty work there can be a little bit of a hassle. That being said, the group I joined is mostly people seeking help, so you don't get a ton of the "how easy and reliable it is" but more of the "I'm having this or that problem." Most of which boils down to problems from the install or existing problems with the engine itself, not problems from the fi-tech.
Now that I've said how great it is for me, here are my biggest issues I've seen personally. The temp sender is crap, just buy a $
15 ACDelco 213-928 (I'll confirm this is the right one when I try and install it Friday) and get the right temps off the bat. And be aware that it likes to do a prime shot for easy start up. This isn't a biggie, as it can work most of the time, but I have noticed that it can cause my engine to flood or start too rich so I have to open up the throttle blades for more air while cranking. Easy solution is to remove the prime shot completely and add fuel to the crank.
Like
@mrk5 said, there seem to be some growing pains. Seen first as not being able to keep up with demand, and now as some customers not getting their returns/replacements promptly. But also, as pointed out, there is a pretty big community that has jumped in and is pretty helpful.
If I had need of one again, would I buy it again? Yes, I would. But as also mentioned, I wouldn't try the FCC, as there seems to be better more reliable options out there.
-Jacob