From this video, I'd say the Legion's trigger is close to, if not exactly like, the one in my P320. That alone makes it an upgrade from the other P226 models. I'm very happy with the P320 trigger, but have to say it requires some practice to avoid it firing sooner than you expected. VERY short travel and lighter than a stock Glock trigger.
The checkering on the front and back straps would of course be judged on individual preference.
I think a Sig fan, collector, or someone looking for their first/next P226 would be wise to consider this one. If you already have a P226, you should try the Legion or P320 trigger to see if that's worth the switch. Heck, you might decide the P320 price, striker firing design, polymer frame, lighter weight, and size/caliber conversion kit features make you like it even better than the P226!
I have the P226 MK25 and the P320 with 2 9MM frame/slide parts: Full and Compact. IMHO, the P226 is my favorite to shoot, but for training, carry and competition-style shooting, the P320 wins.