It is worth adding here that starting-price odds on horseracing - which are the default odds you'll get if you just walk into a betting shop in the UK and place a bet on a horse - offer a rather high profit margin to the bookies.So any alternative to that is likely to offer better value.This introductory offer will I am guessing undercut Betfair's exchange[ Which itself offers better value than SP] while it lasts,providing the markets are sufficiently liquid.
Liquidity has been good so far - better than I would have expected. At present they are only offering win markets, but I've been told that place and possibly each way markets will follow fairly soon.
Agree entirely with your point about starting prices. The system is outdated and quite frankly discredited these days and is in urgent need of reform. Bookmakers will, of course, do all they can to resist any changes because, as you rightly say above, the current arrangements offer them a large over-round and consequently a large potential profit margin.