I took my RYA2 on board a 6.1m Temptress in Troon (see "Maritime Connections" on the net). I also met the original owner and designer of the moulds - a chap called Giggleswick (if memory serves me). When he retired, he gave the moulds to a Julian Dyson, who then marketed them as JMD boats. They were also built in Yorkshire, but the business didn't last long.
She's not a very big boat (mind you, I'm used to an 8.5m diesel now!), but seemed to handle reasonably well, but you sure get a lot of spray on-board in rough weather. The owner of Maritime Connection had a stainless steel plate installed on the transom after it started to crack when he put a Yamaha 100 four stroke on board.
I looked at JMDs demo boat when the business closed, but decided it wasn't for me.
Hope this is of some use.