Yes & no.... The performance of some 300s & 400s can be surprisingly good. My former Bev 350 could keep up with the Tmax in a straight line. Never mind cruising at 50 or 60, I once found myself cruising at 85 on a dual carriageway on it (I was tired and wanted to get home!). However, when it comes to twisty bumpy bits - the sort of road I ride a lot on - then these sort of scoots tend to be not so good. The ride quality on most of the swinging -engine scoots I've ridden really goes to pieces on bad roads and handling becomes unpredictable - I likened going round corners in the wet on the Bev350 as being like playing Russian Roulette! There again, the Burger 650 wasn't that much better away from smooth main roads!
This is why the Tmax or similar works for me personally - the quality chassis& suspension makes riding so much more fun.