16 aswell yamahas are mint i had an Aerox and it was great until it got stolen... got the video of its theft and they picked it up with its two locks on and bundled it in a tranny van !!!
lol
I found 50cc quite tedious... getting overtaken and all so i packed in after it got stolen and went to trials riding which i enjoyed thoroughly
Geared is the way forward and DT's are a mint bike ...
Dont forget that the test changes in october 2008 so pass your test before then !!!!!