A book doing purely bitcoin has advantages processing it over the books that are adding it to what they have. Whether it is 24 hours or minutes
5Dimes has to review transactions just like they do any other because they are mixed together. Did the player play poker with a player who deposited via plastic? Did the BTC depositor roll his deposit bonus over from the other method he sent in 2 days earlier? Transfers from the BTC-only books often dont have to worry about bonuses or addresses or poker networks or if the customer is generally in good standing and in some cases who they are at all.
This is a good player review and it will be helpful to the player who is used to betting at bitcoin only books. It seems like right now books are adding it out of convenience to their users who think they have the best product. I also agree it would be nice if they processed BTC for free to emphasize the ease of it and see it grow. Making a point to have the transfers quick will be good advertising for the lowwer cost method. Maybe one day they will have account signup designated for Bitcoin users. It could mean even better perks as the costs go down. Right now all the established books are watching bitcoins to see how it will work.