I've actually just started to do this with d4f, to test out a few trading ideas on GBP/USD. The spread of 3 pips is attractive, and I too an just trading £1 a point. I've had instant fills at this stake size, which I imagine is robot processed at this stake size (comments, anyone?)
They seem OK so far, but I'd be interested in experienced traders views on these two points:
1). Although the spread is always 3 pips, is it likely that the spread is biased by them relative to the underlying interbank market, and as such might move against me? I guess I will never be able to tell unless I buy a separate realtime data feed. Should I do this, if so, which?
2) If I carry on (hopefully at least breaking even!) should I consider a real broker rather than a bookie who has - I imagine - a vested interest in seeing me lose...