I've read some posts that speak about both. I need to make a decision quick on which one to buy as a replacement. Save all the suggestions for other brands in another thread. All my gear is Stihl, and I've had great success, and am not about to venture off into another manufacturer at this point. My Stihl FS85, six (seven?) seasons old, gave up the life this morning. It has been a great piece, served me very well over the years with heavy use. But, it is locked up, and I need a replacement. My needs are primarily for string trimming turf. I believe my FS85 has been used 90+ percent of the time as a string trimmer, trimming lawns. The other time it has been used to drive a 0 Degree hedge trimmer attachment, with a little 8-tooth blade work. From that profile, a powerful trimmer is not what I need. Rather I need something that runs well, light as possible (both 90 and 110 register the same weight), and will take an occasional gearbox change. It gets used 1.5 to 2.5 hours per day, mostly toward the 2.5 side. From reading many posts, it sounds like most folks like both, but the FS90 may have some troubles. Who has both, and how do they compare, especially with regard to reliability and operation? Also, can anybody provide specifics on fuel/oil mixtures? I have read that some 4-mix blowers do not like anything except Stihl Ultra oil. Does that assessment pass along all 4-mix models? What has been running successfully? Thanks.