actually growing and then using the trees for building is a more permanent sequestration. vs letting the trees down and then decompose. Anywhere that a forest was and is no longer tho, that's a net negative. but only living or non-decaying (i.e. houses & buildings) count. But if the decomposition of the plant is displacing combustion of mined fuels (ethanol vs gas) that's a positive.
We just gotta adapt seals and gaskets! ha, it is kinda annoying sometimes but i havent had much trouble except fuel lines and even then, it's fine once you get the right lines. Personally i'd rather replace some repalceable parts every year or so than seak out ethanol free. it is kinda annoying but not that big a deal and probably for the best (IF they'd make he ethanol more reasonably - separate rant)