Versions 1.2 and 1.9.1 are abandoned wallets which were supposed to end up on their own fork. Version v1.1 is wallet that is supposed to continue working after hard-fork but it
seems it is accepting PoW from all wallet versions so there are at least 3 versions of v1.1 blockchains:
1. One where PoW from 1.2 and 1.9.1 miners was erroneously accepted, PoS blocks by 1.1 will cause 1.1 node to end up banned.
2. One where PoW from 1.2 and 1.9.1 miners was not accepted but PoS blocks will be rejected anyway because nodes are on very different block heights (based on number of PoS
blocks each of them staked for themselves).
3. One where everything is perfectly fine, wallet version 1.1 PoW mining works and PoS staking does not cause forking - even nodes you mentioned are not complaining on submitted
work which means it is compatible with your version of blockchain but here is the kicker = your blockchain is shorter (less work done) so please upgrade to our version. Yet another
version of partially tested wallet in a situation where half of network didn't even switched to 1.1 is horrible idea.
Say I take your suggestion, delete my chain, restart my client sync to yours and mint a couple stake blocks. We will STILL be in the exact same situation we are now, because my client and anyone on my client will go off on their own fork and the pow pools will STILL be mining on their chain. At some point in time blocks are going to be orphaned because the proof of workers wont stop working. Either update and sync with the people staking or continue the work chain, sooner or later everyone will have to choose one and what im not doing is all this work over again. The great thing about consensus is the choice is ultimately yours.