As I'm very a new learner, you might want to take my comments with a grain of salt. I bought a 125 as a commuter (a MadAss 125 to be exact). Within a few weeks I found that it is great on the short commute where I don't have any hills or need to exceed 80km/h, but as I have started venturing further away I find that the 125 lacks power. I did a practice session with some other guys on the weekend. The only other guys there on a 125 has a new CBR125 and he made the same comments.
I'm just about to trade up to a Honda VTR250. Still not a power beast, but light enough to feel comfortable yet will do the highway speed.
If I can also ask an off topic question. What gloves do people use in cold weather. Winter has just arrived and my 'winter' gloves don't seem to cope very well with winter. Any recommendations from those people who ride in cold weather?