I think so, Erin. With the bigger tires you push down with a snap as you hop and the tire rebound helps lift you off the ground. With the freestyle you can get a (much smaller) snap only if you have low pressure in your tire, say 25-30 psi or lower for lighter people. Since I keep my freestyle tire much harder than that at 80 psi, it “snaps” like a piece of 2x4 - i.e., not at all. So hopping with the hard tire is all legs pushing up, with no help from the tire. That Maxxis tire has lots of volume but if you keep it pumped up then it’s the same as my Primo.
If you pull the uni up underneath you well, then most of the action is moving the uni up to the higher elevation; then the actual lifting of your body weight comes as a standing-up thing after touchdown. But since freestyle seat heights are much higher than MUni or trials seat heights, there’s not a lot of room unless you hop seat-in-front.
So if you don’t mind changing freestyle configurations you can lower your seat an inch or two and drop the psi in your tire and go to town hopping. But, like Peter said, it may not handle as much vigor as your MUni. If you have a quality wheel and cranks on your freestyle, though, they will take a real pounding and not mind a bit.
If you are crossing a lot of curbs on your Sem XL then lowering the seat an inch may make the ride much more enjoyable, even with the hard tire. When I ride up/down Manhattan going to Unatics meetings on the freestyle, though, I try mostly to find the smoothed-out ramp spots. If there’s a crowd, I can ride the ramps, but hopping curbs in a crowd, safely and politely, with a hefty backpack on, is, at least for now, beyond me. [hmmm lots of commas in that sentence!]
I don’t know if you’ve seen Mike King’s video Unipsycho Extreme (he’s from your neck of the woods) but it is excellent for this kind of stuff on a MUni. He’s a good teacher and demonstrator. You can get a copy from http://members.shaw.ca/unipsycho/Unipsycho-Extreme/2001.html . He doesn’t address hopping with a hard tire, though. Peter Bier (from just below) can be see on One Wheel No Limit hopping like crazy on a freestyle. If you look at his tire, it has low pressure; I’d guess at around 28 psi.
Good luck and let me know how you fare!