In my eyes FiTech is worse than a MS because you can't get inside it to do stuff. I have had some really bad experiences with both Holley and Edelbrock, miserable support, hours on the phone getting shuffled back and forth, inflexable hardware, and software that does not allow full access, "engineers" with vague conclusions and non-solutions just to get you off their phones in hopes you will give up and live with it. The MS support you get on the forums is 10 times better, you just need patience and a working BS detector.
With MS Tuner Studio will tune it for you (after you get the idle set) but it is (I'm sure) much more flexible and configurable.
If you can get past the FUD surrounding a system like MS you will discover how good it really is.
Myself I would never attempt a TB injected setup there are pitfalls built into it, wet flow, wall wetting, fuel distribution, and other gotchya's. MS has some settings to bandaid this, but BANDAID. It's better if you don't need a bandaid. It's like straight pipes on a Harley there are plenty of tricks to make them "work" (define work) but you can never get ahead of starting two or three steps behind. So port injection is the way to do it, there is a reason OEM's quit using TB injection. And the only reason The FiTech uses it is to make the buyer feel better and get past the FUD, it looks like a carb "it's OK".
It still needs a solid fuel supply and a return system is the only way (in my eyes) to do that right. Many cars will need a swirl pot, as an in-tank pump will suck air. I see the plumbing as more challenging than the electronics on many EFI installs. Especially to embrace safety, a clean install, economics, durability, and ease of maintenance. The injector supply pump needs a flooded inlet and that is next to impossible to do in an old carb type or fabbed large fuel tank, even with a sump (especially for spirited drivers). Even non-spirited drivers will have problems with low fuel levels and hills/cambers, lateral G forces. This is made worse with a single line system, as the only way for air to get out is through the injector.
99% of the FUD around EFI is guys taking shortcuts or trying to use less than ideal components. The real downside of MS systems is the documentation. The doc's were written by guys who have been doing this for years and a lot of knowledge is assumed (tribal). And they try to embrace hardware that is less than optimal or requires complex workarounds (less than optimal). I won't delve into the creative wiring some do or simple mistakes like trying to use non-resistor spark plugs and low resistance plug wires.
I wish you the best with the FiTech unit and look forward to hearing how it works out for you. Not to gloat, but in hopes that they have built a setup that works well.