I've owned 4 stroke 2 cycles. The biggest Shindy 8510 backpack blower and a Stihl FS100RX. I personally will not own another non 2 stroke unit for a long while. I run 89 octane non-ethonal fuel with Amsoil excaliber two stroke oils mixed approx 75.1. No stink no smoke. Both are/where extremely hard starting. Average is about 8 pulls to get started cold this means a minimum of 5 pulls to usually no more than 10! Once running the 8510 is good even though it takes it slightly longer to rap up from idle but that's splitting hairs. The FS100RX was just a terrible machine other than having ok power. It shook like a steam engine and was the worse balanced trimmer I've ever held. Sold it within four months. They may have and hopefully will be making improvements on this 4 stroke 2 cycle system and I may give it a whirl again in the future but for now my 12 year old echo back pack has made me a believer.
My other gripe is how many trimmers have hard plastic handles. Old Tanakas, current Echos and Shindys are the only commercial grade units I'm finding with rubberized handles. I may be older than some of you guys but at the end of the day my hands thank me for the extra dampening.
I tried the Huskys as well and I have to admit I was very impressed. Amazing torque and power. Nice weight too. The only negatives being the hard plastic handles and the engine power head shape oddly enough. I find myself often running my trimmers with one hand for reaching purposes and this means I'm resting the power head against my lower forearm. The power head shape and size fought me doing this.