New shifters: is Acera SL-M360 a good buy and how much better is SL-M310? I was going to buy the Shimano Acera SL-M360 (but now the shop only has the SL-M310 ones), so I wanted to double check if it's what I'm actually looking for. I just want them to last long and do their job properly, no extreme conditions functionality required..

Basically I just want to know if those are good and if there is any difference between the two (and if there is, how significant it is).
Acera is on the lower end of Shimano's line of components for hybrids and other bikes that aren't going to see an exceptional amount of stress. They fit that bill relatively well, but being built mainly of plastic they do have a tendency to wear out over time. Having said that, it's probably the best deal you're going to get in terms of usefulness and longevity per dollar.