The initial stabs are ok but as soon as you bend excessively they really sound wrong as is usual with samples.I hope others can give you tips on getting more authentic.Years ago I had a midi breath controller and I started to get pretty good with it and that fakes brass brilliantly but then you have to learn embouchure and the instrument and now they cost loads.
Sure the bends don't sound life-like, but it doesn't matter, think you ca exploit it. It only matters if it comes across as trying to sound like real horns and falling short. I think they sound kinda funky in a low tech sort of way. Most of it sounds good but the bend down an up again sounds bad on the going back up bit, maybe if it went up quicker, or if it wobbled, or if it stayed down. Use your ears and your creative skills, which you obviously posses, to make new and interesting sounds. :)
That has pitch wheel written all over it. I agree with ted, tough, the first down bend doesn't sound so bad as when it comes back up. But why not just go for legato or staccato lines? Do you absolutely need/want bends? Thoe lines would sound fine without bends, I think, and no one would miss them (except you, of course!).
Brass...but when it's good it really packs a punch. I've just started trying out NI's Kore Player Sound Pack, 'Sax and Brass', and it sounds very good, workable for the 'dirtier' styles, unlike GPO's/Kontakt brass,IMO. You can hear demos on the NI site. All the best!