Is clicky overhaste no longer a thing?

Recently came back and noticed all my clicky overhaste items unlock passive AAs.

It's still a thing, it's just a permanent AA once you use it. Less clutter in the buff window and no more having to click it every 30 mins or whatever.

You can also check in the Inventory > Stats tab your current haste percent. The normal maximum is 217%, with the best items and spell haste. That includes regular haste and overhaste.

It can go higher sometimes, depending upon special stuff/songs/clickies/AAs, but that usually is temporary for a short time.

Indeed.

You start with a "natural" haste value of 100%.

Haste on worn items ("v1") is up to +45 %. Items with different values don't add up, only the strongest will have effect.

Then spell haste ("v2") up to +70% (depending on the spell) adds to that. Again, different spell haste doesn't stack, only the strongest applies.
At this point Haste is soft-capped at 200%.

You can go over that with Overhaste clickies / AA ("v3") , up to +17%, so you can reach a long-time haste of 217%.

Bard song overhaste is "v3" as well, but is higher than just 17%. Again, neither multiple songs nor song plus AA stack up. Only the strongest effect applies.

The hard cap you can reach with all above is 225% Haste.