The reason for the extra length in frog rods is the extra leverage. That few inches can make a whole lot of difference. The other aspect of a frog rod that you need is TIP. It won't matter in the slop but if you are trying to walk a frog in the open some tip give will help you get it walking. I use two frog rods...
In the slop I use a Dobyns 736 so that I have the added power to get them out of the trash without a problem.
In the open water I turn to the Dobyns 735. Its a little lighter rod and its got some tip. It makes it easy to walk the frog but has plenty of backbone to sink the hooks and get them moving.