Whilst much has been added in SuperLemmix, some features haven't quite made the cut. Note that these features have, at present, only been 'commented out' in the code, and can (relatively) easily be added back in if there is enough demand to do so:

Online Features (including Style Manager) are no longer supported, due in part to the updates to the Default & Original styles, but also because I don't have anywhere to host this feature at present. If SuperLemmix gains any traction, I may consider re-implementing this is the future; for now, Styles will be periodically updated on a manual basis and made available from this post/board at all times.

Hotkey presets have been removed and instead there is a single "Classic Layout" which is recommended for use with Classic Mode. It's also similar to the previous "Minimal Layout", and so forms a good basis for building your own hotkey Config.
You can, of course, simply copy over your existing hotkeys.ini file from NeoLemmix if you wish to continue to use your familiar hotkeys with SuperLemmix.

Removed support for Postview Success/Failure Jingles. I personally find this feature a bit tacky, buuut if enough people like it I guess there's plenty of room on the Audio options tab.

Removed option to switch between Release Rate and Spawn Interval. This is a personal choice based on preference for the original way of displaying this feature. Again, if there's enough demand for it, I'll bring it back.

Removed option to hide Advanced Options in Level Select screen. This seemed superfluous and was taking up space in the Config menu, so it's gone.

Removed option to force default Lemming sprites. This one is gone for good; if a designer has spend time and effort making sprites for their levels, they ought to be showcased as intended. As the creator of the Lemminas, I'm hardly going to support a feature that will override them!


Removed option for Compact Skill Panel (the new panel basically
is a compact panel with 14 available skills).
Replays now cancel upon re-loading a level (previously, the current replay would be pre-loaded when starting a level via either "Retry Level" or "Level Select" from Postview and would have to be cancelled manually). This was originally intended to be a Classic Mode feature, but I've decided to push it forward it as a Global standard.
Feedback is wanted on this feature; if people would prefer this to be optional, I'll look at implementing it for next time.