I run a 100mm stem.
The way I use the pack most of the time is as an agressive trail bike, BUT I also use it for shuttle runs and freeride too.
I like to be fairly stretched out up front, and I don't feel that I need a real short stem. I've used shorter stems on Dh bikes obviously, but after trying shorter and longer stems, on those bikes the shortest I went was about 75mm.
If I use a smaller stem, I find myself wanting a bigger frame, and then I have a "huge" frame and it feels like much more of a dog on trails, so with the top tube/stem length that I currently have, I feel like I have a fairly nimble bike. I don't have any problems controlling it at speed or going off drops, but I'm very used to this stem and TT length.
My only advice as far as this is concerned is that you should do what you like and what feels right to you. Just because someone else uses a certain length stem, don't think that you have to do that to be happy. Some people can get pretty adamant about what length you *should* be using, and sometimes they have valid points, but when you take it into account and still find that you like something else, don't feel like you are "missing out".
I'm lucky because at my size, I always choose the "medium" frame (for the most part, after going over the individual specs and making sure they jive with what I like). Medium just works for me, and I'm just at the right size where I don't feel like I'm really "in between" sizes, at least enough to make me 2nd guess. As I stated above, I'd rather have the slightly smaller bike.
