I use 25 1 1/2 and I draw with an 18 gauge ! Works like a charm!
I found that the 18 gauge chews up the rubber stopper on multi-use vials too much so I switched to 20 gauge to draw.
I also find it easier to push oil-based gear through a 1" 25 gauge pin than a 1.5" 25 gauge. So at least once a week for 7 years now (HRT) I've used 25 gauge 1" (even in the glutes) and never had a problem.