Many thanks to all,
Finally I went to the shop, tried both 70-200 IS versions, and while the f2.8 (tried 2 copies) was impressive in built quality , the f4 version was remarkably sharper wide open @ 70 and 200mm.
So I bought 2 lenses, one 70-200 f4 IS and one 50 1.2 L and I'm very very pleased with their performance.
Best Regards,
Ioannis