I think the dual trim mono is the best, I've had all three versions but the extra splay adds to the cleaning ability. The only down side is that if you don't do the frames you might touch them by accident. From my experiance flocked brushes have more scrubbing power and bring frames up nicer, but much less rinse. My ideal brush would be the gardiners design but with flocked inner bristles, great scrubbing power and still good rinse. Simon.
Have a good look at your flocked brush I'm sure you'll find the inner bristles are not flocked.I find the flocked has more scrubbing power but is prone to holding the dirt.
Ive had all the gardiners brushes and have to say that the mark 2 version of the dual trim was the best, I think the splay on the newer one too much...