It is a big improvement, but you still have to be careful about flow rates. That has been my experience. Our nozzle has two positions, i always fill at the slower rate.
I don't know what it was like before but I have to fill VERY slowly otherwise it'll overflow the neck. I can't even get to the low speed nozzle position. Not a real big deal but I have to be very careful. I never let the lineman do the filling.
It helps but you still need to be careful as it starts to get full.
Related, if I had it to do over again, I WOULD NOT install the vent kit. My hangar has a constant smell of fuel now and it's coming from the vent. I'm using auto fuel so I know this makes the situation a little worse as I don't get as bad a smell with 100LL.