So far I only noticed one small bug, besides the missing "minimize to dock"-button for the non-standard skins:
When I untick "Overwrite archive on update" - then close Impulse - then re-open Impulse, I noticed that "overwrite archive" is again ticked. I can untick all morning and it is still ticked whenever I open Impulse.
Rebooting between attempts of unticking doesn't work either. Other settings like "Disable user-skin" seem to work normally.
As a feature, I would like to be able to move the default shortcuts from one tab to the other as well.
For example. I have created a "MyColors"-tab and would like to move all MyColors-suites to that tab, instead the default "My Desktop".
Otherwise I have to say congrats: Impulse seems much snappier now, and there is even a throbber.