Hi Manny, I have been playing my C trumpet a lot for about a year. I would say more C then B flat. When I go into the upper register the trumpet seems to back up on me. (from about G above the staff) I can play the exact same music on B flat and I don't have this problem. I have noticed that I can come in with soft passage more easily on the C. I seem to get tired quicker on C, I think because I am pushing up high. What do you think?