I think I can tell you why many didn't like it in the past - end user couldn't tune 'em. The preset 'factory tune parameters were IT, period. 'Factory wouldn't release the access codes.
I believe it was GT38 who informed me that this issue has recently been eliminated, however.
Mine started off installed incorrectly - the throttle position sensor was wired backwards - the DFI controller thought it was WOT when idling and idling at WOT. That wasn't a good combination. Once I got that fixed it never would run. I sent it back to Roush (at my expense) and they swore it worked there, but when I got it back it still didn't work worth diddly squat. I'm into it about 10K by now. The DFI controller was an Accel. I had gotten (from Roush) the magic token to use the "pro" key which opened up the entire program. After I got it back I figured out that they hadn't populated the altitude compensation table. I took it to a tuner who was trained by Accel and finally got it running. Roush promised to refund a portion of their charges and cover my tuning but never did.
I've since heard they have gone to two different DFI controllers. One was the FAST setup, but I don't know what they are using now.
Their DFI setup looks like Webers, which have some very counter intuitive setup rules. The throttle blades at idle to about 70% throttle produce turbulence, but beyond 70% there isn't any so the fuel doesn't mix as well, and essentially becomes rich. So you actually have to lean it out a little beyond 70%. I doubt a "self learning" system like FAST will close the loop around this anomaly.
They are password protected but I can predict what the password will be.
Additionally, of late, there have been a lot of Roush engines that consume huge amounts of oil. One guy on the Cobra forum today said his repair bill was as much as the engine.
Search for "Roush" at
www.clubcobra.com.
I will recommend AGAINST Roush...
Part 2: Yes, the Roush 427 here is a Windsor based engine ("Small Block Ford"). They are real torquey. Mine was 550HP, 500 ft-lb. I've heard they claim more now.
They do sell a 427FE (based on the Shelby aluminum block). I've heard they are very nice engines.