@Hayabusa...I started tuning cars for drag before I got into drifting, so I tend to set up all my tranny's almost exactly how you explained. I use and abuse the gearbox while drifting though...I'm up and down through that thing like a madman.
@OP, to me, using 2nd and 3rd as your main gears seems a little strange. Most people I know tend to make 3-5 their main gears, and use 2nd only for consecutive slow corners (like the S-bend at Indy Road Course). Note that only applies to 6 speed transmissions...5s and 7s are a little bit different
I use A-Ring Mini Reverse as my test track. In all my cars over 450ish bhp, I'm in 3rd and 4th gear the whole time (on an ideal lap...I'll use 2nd and 5th if I make a mistake).
I use a fully customizable tranny on all my cars. That's probably more out of habit than it actually being necessary, but that's how I dooz it. IMO, a good tranny tune is the difference between a good drift car, and a great drift car.
That said, just the other day, a fellow GTP drifter (and a reputable one at that) was saying that in pretty much any JDM turbo car, the stock tranny's are actually pretty good. The added bonus of running a stock tranny is that you don't get the annoying whine from the gears.