I'd go with the FAST (formerly SpeedPro) with the WBO2 option. It makes tuning a lot easier, you don't need a dyno to do it and yes, you can run it in closed loop (with the WBO2 active) during normal use. Basically, you get a base map to run the car on, drive around with a friend with a laptop to do some dataloggint and it tells you what the A/F ratio is (ie how far off it is from what you enter as the desired). Then you just adjust it to within about +/-5% and you're done. Very quick and easy. And it has a nice user interface. The TEC used to be a little confusing to tune unless you'd done it before and their (direct) support is very poor. There are some distributors however that are very good with the unit. As for the Haltech, I know they were behind for a while and I can't really comment on the E11 as I haven't used it. For more info on the fast, try the Buick GN forum. Lots of experienced people there--not only buick guys either:
http://www.turbobuick.com/
Mike
PS I know Wayne Presley sells the Electromotive TEC unit for use with his individual runner stack EFI systems, so you might want to give him a call too:
www.verycoolparts.com