tlw
I'm not a drummer and certainly no expert on particular kits, but when you say it's a small hall, how small and how many people are likely to be in it? Is the hall acoustically lively, dead or somewhere in between?
As for shell size my observations of drum kits over the years is that smaller shells doesn't necessarily mean a quieter kit. Piccolo snares for example can be incredibly loud and penetrating as can small toms.
If volume is a serious issue it might be worth considering an electronic kit. They look different and drummers seem to either like them or hate them, but the minimum volume they can be run at is much less than most acoustic kits unless you've an exceptionally skilled drummer with a very delicate touch.
I don't think volume will be a big issue.
I unfortunately don't have any details on the size of the hall - I'd reckon maybe 100 x 30ft, but we play with a piano, guitar, 2 low brass, 1-2 trumpets, 3 saxes, and several high woodwinds and no one has EVER complained about it being too loud - generally they say it's too quiet. If anything like that does happen on account of the kit, the drummer is flexible enough to use brushes or and/or a combination of styles to better match the volume level.
As far as acoustics, it lies a bit in between, but certainly on the "deader" side. Lots of really thick, cushioned chairs and carpet through the room. not much of an acoustical change when people are there, but BIG difference when the chairs aren't on the floor.
I avoid electronic kits like the plauge - I've just never been able to like them, after trying 3 different kits. They're fun to play on, and it's nice to practice without disturbing folks, but I find that they're not durable enough, seems to be darned expensive for one with decent sounds/build quality, and I just couldn't get myself to BELIEVE it was the real thing. Not sure I mentioned that we don't really have a proper sound system anyway.