Buzzing, not so bad ... ergonomics, for me already

I used the MX518, but after 5 years broke (by button), then the MX Revolution. Now I was looking for a mouse with min. 5 keys. Since I had the MX518 already, I thought, with the G500s I can not go far wrong with respect. Ergonomics ... Well, I was wrong. I had 30 minutes already use an aching fingers. Either (and / or) this is due to the, compared to my old MX518, other surface, in contrast to the pleasant - to the MX518, roughened at the G500s and is hard, or - I'll call "velvet surface" some other keys. By surface I have the right edge between ring and little fingers felt clearly what was very uncomfortable after a short time. Furthermore, the mouse wheel is much higher and in front of it sits the switch for the running modes of the wheel, which makes the mouse are quite different in the hand and led me to a cramped hand after a short time. I must say that I relatively small hands - have, however, the old MX518 perceived as highly ergonomic, the G500s however, not at all! So probably a good mouse in principle, but I personally can give you for the shortcomings I have mentioned more than 2 stars!