Interesting proposal. The concerns I'd have include:
- If a vote must be used to initiate the hard fork, it should be 95%. Note that this concept only became necessary because of the XT code fork. Otherwise, we could of just set a date in the future and asked miners to upgrade by then.
In the presence of the many BIPs, I think a supermajority criterion is needed. I am not sure why 95% would be better than 75%. I think 75% is enough, and I think 95% might not be reachable. Of course, if a consensus could be reached and "bitcoin-core" or another project convinces everybody to use the SW, then the new BIP10X protocol could be simply activated at a given block height.
My assumption though was that we are dealing here in a somewhat competitive environment between different proposals.
It should be 95% for supermajority. BIP 101 is idiotic for using 75% and calling that the supermajority. All previous BIPs that had soft forks used 95% of the last N (usually 1000) blocks. Since this would be a hard fork, it should definitely have at least the same supermajority standards.