I would like to see the hooking option completely removed. It is BAD BAD BAD BAD BAD BAD BAD BAD. You are saying "use my library, or someone else will completely bork your time sensitive addon". It goes against everything we've always done with addons-- safe hooking, shared event handlers.. everything.
Your addon should NEVER affect mine if I choose not to use it.
The rest I'm completely okay with-- but I would liken this to malware. I think it is a bad idea.
BigWigs won't use any throttling, since it relies on getting it's messages across asap.
BigWigs syncing mechanism doesn't require any libraries since it sends one prefix and listens to that one prefix. Check the Comm-1.12.lua in the Ace2 branch for BigWigs.
Using libs for a comm thing that is under 20 lines is overkill imho ;)
P.S. Checking your code I see if someone doesn't use your lib the messages get sent at normal prio, thus not being at the highest it can be. So if someone uses an addon that uses throttlelib alongside BigWigs messages don't get the highest prio? bad...