My first impulse was to say that an increase in funding for grad students should result in better grad student instructors, but as always, things aren't that simple. Up to a point that's true - as I said above, good grad students (in certain fields) won't come with no funding, and if you paid insanely high funding, you'd probably get top grad students too, but what about reasonable funding - does more money equal better grad student instructors? In general I would say "no." What's most important for grad students is what professors there are to work with. A couple thousand extra dollars a year isn't going to beat out having respected professors in the specific field the grad student wants to study.
I can't speak for all grad student instructors either, of course. I'm sure some departments have first years that teach full classes which can be rough, but I think generally that happens with classes that have less lecturing (e.g. a speech class where a lot of the time is given to students giving speeches). Also, I know my department is a top 50 grad department, but not every department is that way. I'm sure the ECE grad program is much better than mine, but I'm sure some are lower ranked too.