Commissions are low, 40 cents per 1000 shares. Standard propreports statement is fully opened. All fees are without extracharge and rebates are set according liquidity flags. But I suppose result may differs if I'll trade directly with 1:1 leverage and overnight possibility. Am I thinking in a right way?
Seriously, if you think your broker is manipulating "you" or you think your broker is doing something illegal...
Its easy to fix your problem...close your account and get a new broker...end of story.
Yeah, there have been cases of brokers doing something illegal but rarely via the situation you've vaguely described. I'm also shocked you trying to link such a possibility via the difference in your backtesting/paper trading results in comparison to your real money trading results of a thinly traded 5K volume stock.
Seriously, did your backtesting/paper trading results take into account how thinly traded or illiquid trading a 5K volume stock really behaves ? I seriously doubt or else you've mentioned such along with specific details.
Get a new broker and stop trading thinly traded stocks that can easily move strongly (down or up) whenever someone mentions its name on a yahoo message board, twitter or at the local barbershop.