I've sent them an e-mail earlier today, but they are closed until 12th Apr for holidays, so not expecting a reply any time soon.
Seems they are designed by a guy at Solent Model boat club, so may try contacting them so see if I can get a reply sooner.
There is a big price difference, £30 versus £90 or £140 (and the last 2 require an amp too), so as I said, may just hang on until I get to CoalVille show in 10 days time. Hopefullu can see and try there, rather than just looking on the net - not sure which traders will have any units, but sure some will.
The Graupner appeals, but £140 is a lot to justify
Chris