I actually don't know, I've wondered about that before. If it's a mining pool then theoretically customers could migrate if an unsavory decision was being made. I'd guess that kind of majority creates a vulnerability to potential attacks by the pool operator? Maybe that's something we should all focus on, improving mining pool hash distribution.

I have also spoken about raising the minimum block reward from 0.0001 to 0.001 (if it drops below 0.001 at the millionths block, which I haven't been totally convinced that it will). Such a low reward (0.0001/block, ~0.05 UNO/day, 1/20th of what it is now) may make hashrate distribution even worse. In the telegraph app recently it seemed like 3 of 3 people said if it goes to 0.0001 we should keep it there. I'm of the opinion that we should wait and see, but reconsider if hashrate &/or distribution falters significantly.

I'm also not sure about orphan blocks, can anyone comment on that? Is it a problem? IIUC, it's about UNO's somewhat fast block generation rate (3 minutes) coupled with the sometimes significant shifts in hashrate (with the coin ranging from about 1-10 PH/s lately). I suppose it is "inefficient", but it doesn't seem to cause any significant issues.