There are high-walls, and there's everything else!
I am admitttedly VERY biased in this respect, but I don't know anything that any single shot rifle will do in the hunting fields (other than handle rimless cartridges) that Browning's old design won't do just as well or a little bit better.
This said, I have a Ruger #1 offhand rifle, a Ballard Pacific and a Maynard #9, but if I had to give up all my rifles but one, the last to go would be a 'wall. Call me an extremist, and maybe I am, but it works for me (YMMV.)
Dale hit it on the head when he mentioned that the only reason for the low-wall was to ease placement of small (read, "pistol length") cartridges into and extraction of them out of the chamber; and if you want to go with a small cartridge, by all means use a low-wall. For truly rifle class cartridges up to and including the big .50s, the high-wall will get the job done for you with no fuss and no bother. If you go with the modern-built high-walls, you can even get rimless case extraction and although they lack the soul of the originals, these new high-wall adaptations are really shining on the BPCS front, which was designed after all to simulate hunting.
All for now, HTH, the Green Frog