In general, I think SciTwi is an interesting contrast to Pony-Twi (even when Pony-Twi is an EQG); presumably, this is how Pony-Twi would have developed if Celestia hadn't forced her down the princess route.
EqG versions of Rarity, AJ and Dashie aren't as good as their pony counterparts; Pinkie and Flutters seem about the same, and of course Sunset is unique to the EqG universe (and a former pony, so... yeah)
A lot of that of course is that the Pony characters are much more developed, being well established in their respective careers, while the EqGs are still at school.
Well, she does when Ponied Up - but otherwise is just really, really fast because Geode.