For Christmas I got an Omega #6126, love the handle but the brush when wet is pretty floppy, seems to be because the loft is so tall. It doesn't seem to lather very good with creams but ok with soaps. My only brush experience before this one was a VDH cheapo boar and a wee scott. Am I doing something wrong in the lathering? Is it possible to trim a brushes length a bit to make it a bit more stiff? Other than the lack of lather ability I like the brush.
You really don't want to cut the tips off the hairs. Instead wrap a rubber band around the base of the knot.
Instead of the rubber band, change how you grip the brush. "Choke up" on it so that you holding the bristles between the thumb and first two fingers. That will shorten the working length of the bristles making it less floppy.
Good advice above. If you trim the bristles, they won't split and the brush won't be any better than your VDH brush - maybe worse.