I've seen the SLANTED MOBILES while watching US Harness racing on SKY.
Trouble is that they still only have a restricted handicapping spread and given our handicapping from the inside out at the moment it would mean the higher grade horses would get a start off the gate with the added advantage of track camber to slingshot them into the race.
I think my idea of a monitored start with responding devices on the horse's head or in the cart would give you an unlimited handicapping spread and hopefully better betting races and an increased turnover..
As far as cost is concerned there may be a portability between clubs.
At the moment you get an odds on pop in a race and even if they are off the Second Line its Ground Hog Day when after 500 metres the hotpot whips around the field to take the lead and set the pace.
Once he's there it means that only one or two other horses are usually a chance so that a 10 horse race becomes a 3 horse race.