I have an FS250 with handlebars. I bought it used for about $350 about a year ago. We live on 55 wooded acres with MANY saplings, ranging from beauty berry to most all the species of trees on our property: oak, sweet gum, pine, hickory, elm, etc.
I bought this brushcutter specifically to thin out these saplings. I am extremely satisfied. It is true that it is fairly heavy, but not too heavy as far as I am concerned. It has a 2 cycle engine. It starts and runs very well. It seems to have plenty of torque. I have only used 8" blades so far. The limit to how big a sapling I can cut is the available radius of the blade. I hope to try a 9" blade in the near future.
A three legged blade works very well on bramble, briar, etc. I actually used the string trimmer head along our roads last fall and was pleased with that also.
Personally, I adhere to the notion mentioned on TBN often about how you can't have too much tractor. I apply that to brushcutters also. I suppose I would have gotten an FS350 or even an FS450 (not sure of the model number, the one above the FS350) if I could have justified the expense. I approached it from a similar point of view to choosing a tractor, what is big enough to accomplish what I want to accomplish (my tractor is a Kubota L48TLB).
MikePA's FS130 is clearly a more modern trimmer, but I don't think mine weighs much more than his, due to the difference between the 4 cycle and 2 cycle engines. Can't say for sure that's true, but that's what I remember from my shopping times.
Good luck in your research/purchase.
Michael