Russian / Royal poker (version of Carribean Stud)

There is a version of Carribean Stud, called Russian Poker. Rules are same as here. I know this topic have been addressed in the main wizard's page, but so far I haven't seen a playing strategy or a house edge estimate anywhere. I mean, casinos are unlikely to put a game out there, without running the numbers first. Another reason is that I have seen some methodical looking gamblers frequently playing at these tables for a while, always on max limits, before they got barred. Might be a coincidence, but I haven't seen them at roulette or other games, and the whole idea of barring someone is kind of interesting. Usually, they don't even barr you for counting cards here, just move the cut card up the deck.

If you could buy a 6th card in Carribean stud, and all combinations were paid out in the end, what would be expected return of a 6th? Let's say you are sitting with two pairs (2-1 payout), straight or flush not possible, and can get the 6th card at the price of ante. It is possible to improve to full house (7-1) or pair up the your current 5th card, which would be additional payout.

The game may not have an overall house advantage, since the ante is not paid when the dealer qualifies. This is a big difference from the other games like Caribbean stud and Oasis poker.

As for the strategy, there are so many options before the dealer reveals (exchange any number of cards, buy a 6th card, exchange one card again if you buy only one card, etc.), and after (force the dealer to exchange a card), that it would be quite a project to work out out the strategy and house advantage.

Check out this wiki page for the best rules I've found: http://en.wikipedia.org/wiki/Russian_Poker