I bought a set of vista nsc 20s recently and i'm just about to send back the 5w lamp and one of the batteries, the lamps got a dodgy conection inside it and keeps flicking on and off and the power socket on the battery has pushed back inside the battery housing. Other than that they've been really good (the nightstick battery system especially).... the 5w lamp deffinately isn't up to trail riding on its own though, which is probably why its bundled with a 15w too in this package ;)
I too would probably go for the lumicycles if i was buying now... but then when i got the vistas i got them for £100.