I've been using a Lane Shark LS2 for the past 8 months, also recently rented a SkidSteer with HD brush cutter that would do up to 6" trees.
The Lane Shark shines in the versatility department as you can rotate / flip the deck out 90° and run elevated straight down a path or line to cut limbs or brush back as you go. With the deck in the standard position in front of the FEL, it does the same job as a SS brush cutter until you start getting into bigger or denser stuff, which is where the SS brush cutter will be more efficient as you can get through faster with less extra passes.
I rented the SS & brush cutter to get through some of the thickers areas of our woods we were cutting trails in, it was twice as fast as the Lane Shark and handled thick vines without them getting entangled, but couldn't reach as high, so used the Lane Shark to go back and clean up the higher sections later.
The only issue I've had with the Lane Shark is the rear back plate bending out a bit, fully my fault, was fully down on the ground cutting going forward, cut through some bigger trees and the back plate got hung up on them as I tried to keep pushing forward.
Maintenance on the Lane Shark has been minimal, have flipped the blades and about to install a new set as I've worn down both sides of the originals already. Not the easiest task to unbolt unless you have a 2nd set of hands to help.
If I had to do it all over again, I'd do the same; Rent a HD brush cutter for the big stuff or large projects, but I use the heck out of the Lane Shark for a lot of brush and branch maintenance around our 20 acres.
Hope that helps a little
Best regards,
Greg