I have m5.2s that I've had for about 4 years. They're amazing. They stay on when I want them to and come off when I need them too. They haven't broken and they are fairly lightweight. I like them better than my p 10s that I have on my new skis.
ive got a pair with piston controll and they work really well. you can leave the piston off in powder or park for a soft ski, or you can turn them on to stiffen the ski for high speed and reduce chatter