How long do your trimmers last and what type do you use? Last year I bought 3 brand new red max z2600 2-cycle 25cc trimmers and everyone of them is worn out. They are all getting new rings and freshened up right now. I am thinking of switching to a Stihl 4-stroke. I just want a capable trimmer to last more than one season. I am also thinking of leaving the guards on this year too. Any suggestions?