It's kinda a to each his own thing I guess. But you said it best, the manual guys have to constantly let off the throttle....well, do that in the 1/4 and your et's suck with an automatic.
I'm not busting on you by any means, It was just an opinion. If a 9 second guy aint running one, neither am I.
I do think that money is better spent elsewhere, but this thread is about turbo's so I will offer my experience. I have a GT6131 with an Orange Stripe converter (3K stall). It will work great with a D5 as well. Even for a standard bearing turbo it hits hard....real hard. Boost is as quick if not a tad quicker than the stock unit. Right around 5 psi it lurches to 26 in a split second.
Fun as Hell!
I know youre not busting on me. You were just offering what you know. No worries mate.

We're all in it together here.
The 9 second guys arent running it, amongst a TON of other things, because they dont ever
get out of their throttle. theyre purely trailer cars, that get taken off the trailer, get run down a 1320 foot straight strip for 9 seconds a couple of times, then get put right back on that trailer, and trailered right back to their garage, where they proceed to take half the car apart again, and make 85 calls to jack cotton, cal hartline, chris kokkonis and mike licht, to 'improve' more things. (ie to fix half the crap they just broke lol)
Any time ANY turbo car drives in the street, you let off it's throttle THOUSANDS of times a week. the ONLY purpose of a blowoff valve, is to vent the air that gets immediately trapped, in between the still spinning compressor wheel, and the now closed throttle body blade. The reason manual cars get em, is because they literally get off their throttle 5 times as much as an automatic. (for 5 speed cars that is) while compressor surge (or compressor slam) doesnt really hurt stock applications that much, it can be quite compounded, by these 500 horsepower aftermarket cars. (99% of grand nationals) And while these new turbos are quite strong, some people still like to throw in a little protection to their 2000 dollar precision power adders, by installing a blowoff valve. Sure, 99% of people never have to replace their turbos from compressor slam alone, but god knows I'll be that one percent that does. So the way I see it is, it's cheap insurance. It's either 150 bucks now, or a 500 dollar rebuild later.
(disclaimer: I could be
completely off in this theory, but it's what I gathered from reading this website. If I am indeed wrong, then come correct me. I need all the correcting I can get, before I drop some hard earned money lol)