I don't listen to U2 much these days, but I don't listen to much other rock music either. I think Dave Evans is of some passing interest for folkies, because he used to be one of us - plying his trade with an acoustic guitar. I always felt that a lot of the U2 sound was built around drones, which could be hypnotic (if you liked them) or tedious (if you didn't). Some folk guitarists like to use a drone effect by letting the top and bottom string resonate (when playing in standard or open tuning, for instance) and then playing up and down the middle strings of the instrument. It is a very simple technique - the sort I like best. I would say that Dave Evans used electronic effects to get a comparable effect with the electric guitar. For me it sounded very interesting and different. It is easy to snipe and successful bands and then take cheap shots at them as being "worthy". U2 is not my favourite band, but they have tried to progress musically and have always behaved with a fair sense of basic dignity and decency. That is not something I can accuse all rock bands of!