Hi :)
We went for the BRC system. It's a phase sequential system so it automatically changes over to gas once the revs are right, the engine temp is right and the gas temp is right, but it does it in sequence rather than all at once. It still only takes a couple of seconds, but it is smoother.
The cost was £2323, so we paid more than you can get systems for elsewhere, but tbh we'd rather pay more and have a better system. We really didn't want to go for a cheap system on the Lex. Plus the guys are only 5 mins from where I work so any probs they are right there.
Are you going to JAE? I'll be bringing her along if you want to take a gander! :)