Mowed quite a bit of RCG and young willows/tag alders in an fallow hay field yesterday with the 6' woodmaxx (FM78) flail mower.
I'm very happy with how it evenly spreads thatch. My tractor is a bit under powered for it (28 PTO HP). It does fine in most stuff but in thick/wet RCG and some of the willow bushes bogged it down a lot almost stopping it and needed a second pass. Overall it does what it needs to do and I'm on the fence about whether I'd rather have the 5' model. I did hit something (likely a rock) that has it vibrating a little bit. I'll have to check the flails when I get a minute and see if there is some replacement needed.