Looks like you already got the info you needed.  If anyone else is interested, I had the FS 110 for several years.  It was great on grass and small brush (three point blade) , but just wasn't up to doing small trees with a cutting blade.  I've had a Stihl FS 460 with a carbide blade for about 3 years.  It's a tree eating machine.  Will cut up to 2" on one pass, 3+" with several hits.
I tried all the Stihl blades.  The scratcher works as well as any on trees, but only lasts about 4 hrs of continuous cutting (sandy/rocky soil).  The after market carbide blade is on it's 6th full day of use and is still going strong (though missing a couple of teeth).  As I recall, the carbide blade was nearly the same price as the scratcher.  Search for carbide brush cutter blades.  I've seen posts elsewhere that talk about using a carbide circular saw blade.  Please don't do that as they aren't designed for the speeds or impacts of a brush cutter.  
I used a blade on a loop handle while I was figuring things out, but I won't ever do it again.  It was just too easy to slip, trip, or slide a foot into that blade or recoil the blade into me.  With a handlebar and harness there's much less fatigue and it's extremely difficult to get any part of my body near those spinning carbide teeth.
I also experienced performance/maintenance issues when ethanol came on the scene.  I will not use ethanol gas in my small engines.  I have another post here praising my Stihl tools - I have no interst in Stihl (or carbide blades) other than a very satisfied customer sharing good experience.  I wish I'd found these forums years ago.