So here is a question: Would anyone be opposed to having a system where savage is set up such that there is a savage, savage+, savage++, etc, where groups are required to complete the prior version to unlock the next version, and each step up makes the damage and healing checks tighter? Same rewards come from all the tiers and the only difference is how fast you get them. That sounds like a much better option than going with just one flat difficulty curve and completely locking out rewards for a huge swath of players.

E.g. base savage just gives a book, savage+ awards a single chest on the first two, savage++ awards a single chest on the third and two chests on the first two, and savage+++ is the full reward. Obviously this could be tweaked around, but it would at least give groups that have less time the ability to learn all the fights effectively with more forgiving dps and healing checks before trying to go into a higher tier. This would also cut out the need for a lot of third party tooling since groups could now cover all mechanics in an easier version before doing the full on version.