bruno have you ever tried editing the styles and sounds in the T2 or changing the mixer settings?
You'll find that you can make the brass sounds superb for big band, you can make the sounds as bright as you want very easily, if you want less bottom end then just edit it, Glen Miller songs can be mixed so they sound either like the original, a band of today or even futuristic if you want to go all silly. I agree that the sequencer is a bit weak although I never use it anyway. The Technics have always been pretty good in the Big Band section but you really should dig deep into editing the T2, if you want results you have to put the work in.