Regarding the duplicate coinbase fix, i think we should go with mandating the height of the previous block be set in all coinbase transactions’ nLockTime field. The feedback i got from all miners i reached out to was that either of the fix being discussed was fine. Over other approaches, this one has the added advantage of letting one retrieve the coinbase’s block height without having to parse Script.
If anyone has an objection or a good reason to prefer an alternative approach please let me know.