Ergonomic mouse, but a bit heavy

Most:
I bought this mouse to try to reduce my pain in the arms and hands (high PC use ...)
After a few weeks, there has indeed improved due to the better position of the hand.
However, it took me to buy a mouse pad with wrist rest to avoid the pain
edge of the hand, based on the table.

Cons:
- The mouse is a bit heavy and I regret a little my old mouse, more manageable.
- The two additional buttons are unworkable in practice as they do not fall under the thumb (you must take off the mouse hand, which is annoying) - but maybe for other morphologies, that would be best suited.
- Roulette gives no sensations back, and we do not know if she turned or if the finger slipped on.