well, for 1 the soot issues with HP ultra
2: the gas itself is meh and has bad quality control, when I bought my 881 I bought a 4 gallon case of motomix to 1: double the warranty and 2: have easy to get fresh fuel in each truck which also has the benefit that nobody is using their mix in my saws
well, the dealer took my saw outside, filled it up with motomix and attempted to start as company policy says to do, after almost 15 minutes pulling over a 120CC saw they gave up and put VP in, fired on the first pull
ive ran VP 50:1 in every one of my saws since then, been over a year now and never had a single issue, my 200T sat for 6 months or so and fired on the 3rd pull with it