I finally found a cheap M 200 F4 - tested a bit yesterday evening.
My first impressions: small, light, reasonable sharpness @ F4, quite sharp @ f8. Colors and contrast are both good, better than I expected in fact, and much better than what I could get from my Viv 70-210 f2.8~4. I need to use it more to see if PF is an important issue or not...
I also like the built-in hood, really practical (like on the Viv 105 or DA15/35...).
So far i'm quite happy with that 50€ purchase
(now if Pentax could release a DA 200 F4 Limited, I'd be all over it!)
Thanks all for taking the time to help out!