Well, after I ruined two 120 rolls of Fomapan 100 in succession, the sacrifices apparently begun to work! In my last attempt I shoot the B/W step tablet with different ASA ratings, from 50 to 200. Development time was exactly 10 min at 20 C, 1st min constant agitation, then 10 sec agitation each following min. In those conditions the density was okay in frames shoot as ASA200, so probably the good development time for Fomapan 100 as ASA100 should be 8:30 - 9 minutes. I will post here when I will get results. This data should be applicable to all old-style films like Forte, Svema etc. Now I think if there is a way to decrease the speed of the developer - maybe glycerol in X-tol works like a diffusion brake? In present state the P-C-Soda requires a very precise timing and temperature control - 7:30 is not enough, and 10:00 is already one stop push!