Brush Cutter Options

I'm looking into purchasing a brush cutter to clear out some thick growth on my property. I have been looking around and I'm torn between a walk behind string trimmer and a hand held brush cutter.

So pretty much these -Walk Behind String Trimmers

Vs.

These - Hand Held Brush Cutters

My question is; how well does the line on the walk behind models hold up? Will I be replacing line after each use?

I like having the option to attach a blade to the handheld versions. But I would prefer the comfort of the walk behind.

Let me know what you think.