Thanks everyone for the responses
My Beta is actually generally a first kick starter (but its not interested in any form of crash starting - neither is my back...) and if every time I started it it was on flat dry ground I probably wouldn't have too much of a problem. However I seem to stall with monotonous regularity on the side of hills or on slippery off camber tracks where I have to go into awkward contortions to kick the bike and then my back lets me know all about it.
I don't want a 125 as I like the torque of the 270. There is an evo 4T 300 on the market but its an 800 mile round trip to look at it and then I'd have to sell the 270 in what is a very quiet market - still it may be a better choice than continually aggravating a slow to heal injury or not riding my trials bike at all for a long period of time.
I'm going to try going for a ride on my trail bike this weekend (electric start thankfully) and see how that goes - pity its so damn heavy.
As was pointed out - the idea of some decent capacity electric start trials bike is certainly appealing but makes no commercial sense so it will never happen.
Its also a pity electric trials bike technology isn't a bit more mature (as in economic) - that certainly would have some appeal