I have an account with tradesport and they have MANY weaknesses.
They do not have the liquidity to make all games fair and competitive. They profile one or two games, the rest have a spread of Bid 40 Ask 90.
Also, they go blank all the time during the time you WANT them to be active. Say the game last night for example. The Bears got that long TD to close the gap to 8 pts. Right when the TD is scored for 30 plus seconds the betting screen goes dead..no bid or ask..what the hell kind of market is that??
I will check out this betfair, but I would NOT recommend tradesport for active exchange betting. For long term prop betting, they are just fine.
Bet exchanges are like betting on speed..the rush can be unreal! But you can also lose everything in the matter of seconds..