The 4-mix Stihls are stout! I just purchased an FS 130R for $379. Now let me tell you I wasn't looking to spend that much on a trimmer but this thing is a true machine. It sounds like a small dirt bike running. I use the brush blade and cut saplings the size of my thumb with ease.
The torque is ridiculous. You can put it in the middle of the thickest weeds around then just goose the throttle and it cuts with ease. Super good torque. The head design keeps weeds from getting wrapped and tangled up which is a major plus. It's also super easy on gas. Probably uses a third as much as my old 2 stroke. Much quieter too.
It starts with ease. It has an assist device that makes it easy enough a kid can pull it.
Buy a Stihl FS 110 or 130 and I promise you won't regret it. It's a little more money but it will easily last you 20 years with some care and basic maintenance. Not that I love weed whacking or anything but this thing truly is a pleasure to run if you must trim up.