Love it! Rated 5 out of 5 stars
After a couple weeks of use I love this add-on for portable Firefox's I use for different things, it saves me a lot of time compared to alternatives to get super slim scroll bars.
Though I do have a single request:
*Per-site color options would be the best thing ever!
Thanks for review.
The last dev release v1.0.9pre1 (versions page) has an option, where something like you requested can be set. But this option is not very stable, colors sometimes change twice or don't change, when they have to change once.
The scrollbars and how they are called and rendered by Firefox are the main problem here. There is nothing I can do to improve the option. I'm thinking about removing it in the future.