Pretty sure Demidov had > 10%, IIRC it was somewhere around 20-30%.
Some people posted on 2+2 that he had the same deal equal to a lot of other Russian tournadonks like Vitaly Lunkin. I believe the staker is called gipsy1974 (or it is the other gipsy??? guy).
He had to pay like 30-40% taxes on his winnings too (like Eastgate, although he did try that relocate to London thing before the FT).
Eastgate was already a pretty established player in the higher cash games (1000-5000NL although I don't think he won a lot at 5000) and he tried taking a shot at 10000NL+ on Stars after the ME win. It didn't work out and after losing for a month or three he quit. After his first EPT final table he tried it out again and did better. I'm pretty sure they deposit your EPT winnings in your PS account if you ask them so that's probably why he took another shot