I've got one, its light weight and easy on fuel. Its also the last trimmer to be used as both myself and the guys that work for me prefer the 100rx. The 100rx is slightly heavier and while on paper it doesn't seem like much more in real application it has much more power and is easier to start.
I bought one two months ago, along with another stihl 90, after about 3 weeks the 94 wouldn't idle, still in shop, it rev higher rpm when needed but nowhere close to a 90 in hp or easy to start, the guys wont touch it, they like the 90s, so it turns out being an extra piece on the truck. not worth the extra price.
You can adjust the speed with the dial, allowing you to use lower rpm's around beds. Then when you pull the trigger, you won't accidentally rev up the rpm's. But, if you pull the trigger hard it will go full throttle (you don't have to feather the trigger).