I just bought an older used Befco Flail Mower and must say that it is nice to not have the length of the rough cut mower behind me (I can actually turn around without having to do a multi-point turn).
My cut quality is poor at the moment as the blades are old but I'm going to order some replacement "fine cut" blades and see how they work.
If you can afford one then they are much better for pasture and field mowing. I'm not sure how well they would work with thicker stuff but they may just shred it all up too.
PB