Don't worry, I've had a set of QTP's for 5 years or so with no problems- they're pretty durable, I know I stand on the swicth a little too long most of the time & both actuators still work as advertised.
I'm running a geardrive system machined in Victoria, Australia by Diecrest engineering. I don't think they are available anymore, but you could check. I've been running it for about 4 years, trouble free.