Sounds like your run of the mill cheapo Chinese mouse. If the crappy sensor/weight doesn't bother you at all, I don't see a reason to replace it with something more expensive. Shape is king and you seem to really like the shape.

btw if you want to make it lighter, I'm sure you can just take out the metal plate on the bottom, which will be responsible for a big chunk of that weight. I did the same for a different Chinese mouse I own that also had a metal plate.