Betfair or BetDaq?

Betfair was the first exchange I ever used but after running Betfair and BetDaq side by side, I noticed that there may be an opportunity of making a few extra ticks profit from the difference in prices between the two exchanges, e.g. Betfair may have a horse with a back price of 2.1 and BetDaq may have the same one at 2.2.
I thought I had my first viable system to try. So I set up and account on BetDaq and transferred a few quid to set up a £50 bank. I ran Betfair and BetDaq side by side and took a position (lay) in Betfair when I thought a diving trend had bottomed out and then went to back in BetDaq which had a higher backing price and looked to yield a quickly scalped profit. Sadly not to be. Betdaq has such a lower level of liquidity than Betfair that playing one against the other proved not to be very effective with before the off (10 minutes or so) trading.
Perhaps this isn't the with some fatter races where there is a lot of money floating around but the early evening weekend races I was looking at just didn't have much luck.

Overall, I found Betfair to have not only more money floating around (and money moves the price, right) but it also has an API, so you can set up bots.