Re: New transaction malleability attack wave? Another stresstest?
This is a fine thing to do (though it requires first getting the amount of non-canonical producers down to a negligible amount, something I've been trying to accomplish for two years!); but it does not achieve the goals of BIP62, which is to make transactions involving refunds safe... doing that requires that the solution not depend on miner honesty. 
I actually considered it as first step to pave the way, not as ultimate solution. Besides reducing the rate of rejected legit transactions (edit: just to clarify, the reduced rate of rejected transactions is only applicable, if there a mechanism in place to block non-canonical signatures), users whose transactions are mutated in a favorable format are likely still annoyed to some degree, so it's a bit like shaking a tree, and seeing what falls down (i.e. which wallet implementations are mentioned, if users complain about the mutations).