I've been using AA3 on windows for a very long time and know the program quite well in and out. I recently made the switch to mac because of windows being a terrible, unstable environment for recording, editing, and mixing audio. I'll just go ahead and throw down my list.
1.) Metronome. This is an obvious must.
2.) Group clips function. There is no feasible, efficient way for me to edit multi-mic instrument takes without this feature. Drums are already a pain to edit, not having a group clips feature makes it nearly impossible.
3.) A plugin or feature similar to "beat detective" in pro tools, that will also auto-fill and crossfade split clips.
4.) A hotkey that allows you to scroll/snap to the next transient would be amazing.
I'll continue to add to this list as I get more time with the Beta.
Most of these items are on our feature TO DO list. You might be able to achieve the "jump to next transient" functionality by using the DeClicker tool in the Diagnostics panel. After scanning, transients are displayed in a list and single-clicking each one will immediately select the "click" and allow you to preview it before deciding to repair it.
edit: changed to "single-clicking" to move between items as a double-click will repair automatically. Also, once a single item is selected, the up/down arrows will move between items and update the selection automatically.