Seems identical to betfair.com who typically has more generous odds than the UK high street bookies.

Being in the US, there may be the issue of whether you are acting as a bookmaker (since you can dictate the odds you offer, at least on betfair). You aren't betting against the bookmaker like pinny or mansion, but against other people since bets have to be matched on either side.

I know standard bookmakers are always going to move lines and such to limit their exposure and generate action on both sides of an event but with an exchange it is explicitly you doing this.

Molina