I bought a scythe off ebay a few years ago and it's adjustable - I was under the impression from hours of research and youtube videos, that they all were. Everything I've read talks about "fitting" it to yourself by making these adjustments.
I had to give up scything because it was knackering my knee, but as that has now been replaced (the knee, not the scythe) I plan to give it another go.
My scythe is one of those curvy metal ones, but I have to say that although it does work, it doesn't feel the most comfortable/ergonomic design. It takes a bit of practice and fettling but once you get the motion correct for you, and recognise just how often you need to sharpen it, it can really rip through the undergrowth.
There is a lot of people advising that you need different blades for different jobs, but if you watch enough videos you will find the folk who use a single blade for every job and simply make little adjustments to the scythe or their technique. If you only have a small area to work then I'd be inclined to go down that route.
I have a large lawn (which will always be my ride-on job (as much because I enjoy driving it) plus 3 acres of mixed meadow, so realistically I'm not able to do the job with a scythe, but the plan is to keep the paths clear with one and clear some smaller patches as & when required.