Shimano Alivio M4000 vs Altus M370 shifters I'm planning to upgrade my shifters to Alivio M4000. My old shifters are Altus M370. My question is will this make a significant differrence on my shifting? I'm running Altus M310 FD with Alivio M4000 shadow RD
When you upgrade shifters (provided you have the right compatibility), you're paying for (or trading off between):


Lower weight
More strength/durability 
Reliability 


In the sense that Alivio > Altus, you should be getting some of these. 

However, if your shifters and what not are in good condition (i.e. good cable runs, shifters in good condition, derailleur in good condition), I don't think you'll notice (much).