Previously I was using the RC to 1.20 before the client team at LL managed to bork it beyond recognition. I had skipped 1.19 entirely. Nicholaz has put out a minimally patched 1.19, and Barney Boomslanger has ported it to the MacOS. I am going to test it today on the machines I use and report back as quickly as I can on it.
One important reason to shift up is that the 1.18 client truncates map teleports and building to 768M, even on simulators that go to the 4096M limit. Many mainland simulators seem to be at 768M, though I need to check this with scripts.
I'll report back on both of these.
[Updated: the mainland sims are on the new height limit, it is a client issue.]