You are getting great advice from the posts above. Just to reiterate, bore is less important than how the horn feels and responds to you. Bore is just one facet in a multitude of factors like leadpipe, bell, mouthpiece etc.
Just something I have observed --I think a number of H.S. players want a L bore horn because it seems macho (well, at least for the male players). There is something about saying "my large bore horn still has trouble handling all of the power I put into it." Realize that pro players are about getting a horn that is best matched to them. Let me give you an example. My idol was Maynard Ferguson. Heard of him? Had a huge sound and tremendous power. Guess what he played during what many call his "very best" years. A Constellation 38B. It is a small bore horn. Yes! However, it has a large bell (5 1/4 inches) -and with the other specs -it was the horn for him. I have a "copy" of the Connstellation and it is a very open, free blowing horn. I think it takes more air than most of my MLs, even though it is small bore. Bet not too many of the guys bragging about needing a large bore would have out blown Maynard. At any rate, that said, there are folks who do need a large bore horn. But you would be well advised to try a ML and go from there. Playing them is the only way you will know.