Updated script based on the comments preview script from userscripts.org. Completely rewritten, works with new and old design.
There's still room for improvements for the new design:
Comment style hard to read
Newly added comments can cause problems while scrolling
Compatible with new and old Reddit design
working with https and RES never ending reddit
colorschemes for normal and RES nightly mode in (thanks to gavin19)
Option for auto-expanding images
Option for for autoloading all comments
Skips comments from known automoderators
Automatically retries to add comments if request fails
Option for automatically hide side bar / toggle visibility
Shortcut 't' to show/hide comments in RES
comments added at bottom of entry (Behaviour can be changed in settings.)
If you don't care about the new features and just want the old comment preview, you can disable the features in the options part of the script. There is also an option to change the comment sorting for the preview.
This script doesn't work with new versions of GreaseMonkey, use TamperMonkey instead!
Completely rewritten for new design (uses jquery now)
Removed option to specify where to put comments for different entry types (not feasable with new design)
Added option to skip comments from specific usernames
Fixed RES bug (new comments didn't load sometimes)
Fixed hide sidebar in comment section
Added limit for comment requests repetition
Adjusted nightmode for code and pre blocks, revised css code.
Ignoring entries marked as RES duplicate
Refactored and cleaned up code
Since I'm not planning to add more features, v2 updates will be most likely limited to bugfixes/perfomance.
When autoloading, comments will now be added the bottom of each entry. Comments added by clicking will still be added to the top.
You can change the position of the comments in the options of the script.
I finally added a storing option for the settings. There are two new menu buttons, one to hide/show the sidebar, one for autoloading the comments and images. The script is tested on Chrome and Firefox. Please contact me if you encounter any problems.