Share with some experience from my bigger bike friends, so here
is my advice.
Class 2 bike is usually for "show-off" use one. Go for one only if
you really got the extra money to spare, but don't know where to
use. Usually those from armed force ride big bike - signed on
personal usually got a lot of money but no time to spent. Anyway,
it good to aim big - got target in life better than none.
Class 2A bike got better performance than 2B, but at a higher cost.
2A bikes onwards usually lead the traffic, which is a very big
advantage. Some people think that having a 2A bike is enough liao,
but from what my friend say - when you have power, you will ask for
more power. That's why some people advise to change for a class 2
bike directly rather than going an extra step to 2A first. Do it if
you can endure it.
Class 2B everyone knows the advantages. The only thing I can say
about 2B bikes is - not shiok enough. My advice is - don't invest
on a new 2B bike, not worth it (money wise), if you are planning
for an upgrade in the future.
In summary, get a 2 bike if you REALLY got the money. Get a 2A bike
when you are fed up with 2B. Remain with a 2B if upgrading is a
problem. About bike license, go for as high as possible, just for
fun or whatever reason.