I love gi BJJ, I love TPJJ, and I mix the two...A LOT. Here is a random list of some things I have noticed, off the top of my head. I'm curious to hear what people think, and would love feedback. BTW, many of the problems here I think could be fixed by readjusting/redesigning the moves for a gi and not being attached to "how the video says to do it online" when it is a nogi video. Eddie and everyone else have spent years tweaking everything perfectly for nogi, so don't expect the same thing to be perfect for gi - you gotta use your head!
1/2 Guard:
-It is easier to keep someone flat with grips, so whip-ups are harder to use, especially to sweep (vs recovering guard)
-Grips make a lot of TPJJ moves possible from just a deep-1/2 (or inside 1/2 or whatever you want to call it)
Full guard:
-As noted by others, something similar can be done with the gi, which also has much more rotational force with it
-Grips make it way easier for the guy on top to stay tight and wait for just the right moment to posture hard and slip out
-Gripping the gi in various spots or the belt can really help transition between RG positions, e.g. if you can't get the double-bagger, just grab his belt.
-I have no idea why, but the triangle lockflow series doesnt seem to work nearly as well in a gi. I go for teepees and bolt locks, but I only ever seem to get the regular triangle. I think it is because they can get a grip with the trapped arm?
Twister Side Control:
-Seems to work perfectly, if not better. Because it is more dynamic than regular side control, when the guy rolls out, he really has nowhere to go when you can just grab his gi. Add in lapel chokes even as threats, and guys just give up other positions and subs.
There's a million others, just off the top of my head