As you may know, broadband is usually considered to be anything above 512,000 bits per sec (?). This is very fast and perfectly adequate for demanding online games/downloads and surfing. In fact, some people would say it is good enough for most things. Unless you want to stream films or high resolution webcam etc, I would have thought that 2mb (2,000,000 bps)was a bit over the top for current applications if the extra cost (over 512K or 1MB) was anything more than a few pounds.
One advantage of 2mb is that (I think) it gives an advantage in some online gamers. Maybe they need it.
IMO, 512K or 1MB is likely to be enough for the time being. But it depends upon the cost.