It's not a problem actually, we can try to find some heavy hash alghorithm which require huge amount of memory (bye-bye asics) and which are very inconvinient for GPUs.
This is mostly just another holy war that I'm going to try to avoid stepping into. All I'll say here is that I don't currently intend to explore replacing SHA, and you'll probably have a tough time convincing me that there would be any sustainable benefit.
We don't even need to make them unnoticable. Parameters can vary within the range +/- 20%. I bet it wouldn't be a problem for people even if they would need to drive bike and 5 seconds later it would transform to hellicopter.
Sure, but if you make them too noticeable it just becomes something else bots can leverage, too.
In any case you have the frame-rate inconsistency problem to resolve.
Anyway, the final decision is yours of course...
Not really, anyone can propose a patch. (I'd much prefer it if I weren't the only one implementing changes, anyway.)