Originally Posted by Redbullet

Yes, I assume you are right. Shimano manual should reflect that also, but it does the opposite - thus, it is misleading. My first serious encounter with Shimano was 50% fail. I had difficulties with SRAM systems as well, but all were fixable and fixed.
The funny thing is that with Tiagra GS and SRAM cassette and chain, it is the first time when all my cross chain positions work smooth as they were middle combinations (using "trim" function of left shifter). It is a pity that shifting is partially spoiled. But I start to get tired and I think I should simply live with the poorest shifting of my systems. After all, it is about a cheap (trainer) bike that finally meets all the basic requirements. Hope that hesitating shifting will not prematurely wear the components.
Thanks for advises!