I've had a lot of success with the HP90. I've tuned a couple running 7's (mine included), several running low 8's, and countless more that are generally running 8's, 9's or 10's. There was even one car on a factory 2.4L blower with nitrous that was consistently running 8.50's then later 8.30-8.40 on a completely stock HP90.
Would my car be faster with something like a TH400? Probably, there's a lot going for it with decades of R&D built up for it and it puts forth some key advantages including mature race converter options, less opportunity loss from shifting a million times going down the track, a trans brake for better consistency and reaction times, just a few big ones off the top of my head.
I get called out by a lot of high 7 second mustangs around where I am, I nearly always loose to them all just cause of the reaction time difference between how their cars are setup versus mine with the HP90.