I can't speak to longevity yet. but so far my cuda has never been better. I went firm feel stage III steering box which came with their normal ratio Pittman arm. I also have Firm Feel Upper control Arms. QA1 lower control arms, QA1 adjustable shocks, QA1 adjustable strut mounts. My thinking is it's a bit expensive up front, but these cars are an investment. Do it once, do it right.
Firm Feel was of good quality, customer service was great, and they answered questions as I had them. I believe you would be happy picking up a Pittman arm from them. On the flip side its an accessible part and a Moog arm may work just as well and can always be upgraded down the road if you need to for not much effort.