so far my bike has had not problems what so ever and i have been parking it outside every night and i have been doing lots of biking on very crappy maintained sidewalks. if i can bike on the street i will.
this is pretty much the same shifter i have on my bike except that mine is a 7 speed shifter. i don't think the shifters make a difference. i think it has more to do with your derailleurs and cables.