If you're planning to do an exo cage you don't need to be concerned with the extra weight of the 4Runner compared to the trucks.

I previously owned an 85 truck and now an 89 SAS 4Runner.  If setup identically, the trucks will climb better especially if the wheel base is longer (mine was an extended cab), but the biggest downside is the rear overhang compared to a bobbed truck.  I need the extra seating in the 4Runner so it's a great trade off for me, but for wheeling alone I'd always choose a truck.