Not the first problem in any of my chainsaws as far as hurting the P/C's, or any components of the fuel system. What I do notice, and every single saw I own does it. If you are cutting in really hot/humid weather, and shut the saw off, it is difficult to restart if you let it sit for a while and "heat soak".
They are fine if you restart it within 3-4 minutes, but a 10-15 minute sitting period and they require some effort to start and to keep them running. This problem clears up quickly once you get them to fire, but it is a bit aggravating at times.
What I've been doing, is to take 4-5 saws to the woods, and if I shut one down after using it for quite a while, I just grab another saw and let the first one cool completely down. I suspect the ethanol is lowering to boiling point of the fuel enough that it's causing the restarting "issues" that I've been noticing.
As far as automotive, industrial and Marine carburetors go, NOTHING made of rubber will live long in contact with this new fuel. Viton fuel inlet needles, and accellerator pump cups are MANDITORY. Just ask the Marine industry. Ethanol hit the Marine gas pumps last, and we are selling a lot of parts to folks for Marine carburetors in recent months......Cliff