tjb, congratulations on your purchase decision. That may be the hardest part. I believe the 3710 is the largest Grand L that can still take a belly mower, but I don't know if that is one of your requirements after you clear.
MarkC needs to be severely disciplined, however, for commenting "plus 7 HP". On the Gross vs. Net Horsepower thread we have concluded that the 3710 is measured by net HP whereas the 2910 is measured by gross HP, so that means the HP difference between the two is ... uh ... er ... well, where we are at on that thread is that we are, basically, confused.
Glenn