Mmm i see, they look to have been sawn from a larger sheet and cut to size. I tend to use a very small Bentley probably only five inches long with the jets as close to the centre as possible purely for cleaning outside guttering. Bentley bristles don't last five minutes with hard cleaning, whereas yours seem very hard wearing, a nice length with a handy narrow stock, would seem a shame to hack a full brush down but if you ever bring out some varying sizes it might be interesting.
Do you think there would be any advantage in a deeper dual trim? Say with another row or two or do you feel that you have the optimum dimensions?