I used TST for years until I switched to Sidebery, and I must say it somehow has all important settings from TST (which I supposed to be impossible - TST caters to tweakers in an extreme way) but is also faster (both startup time and day to day) and seem to use less memory as well.
Some things are in unexpected places (for example I expected to reopen a closed tab with right click outside an open tab - reopen closed tab, but it's in the trash icon at the bottom), but I think they are in better places. Sidebery is better designed.
Sidebery can also save your tabs automatically, something I used another extension for (Tab Extension Manager, which loads very slowly)
Some things are in unexpected places (for example I expected to reopen a closed tab with right click outside an open tab - reopen closed tab, but it's in the trash icon at the bottom), but I think they are in better places. Sidebery is better designed.
Sidebery can also save your tabs automatically, something I used another extension for (Tab Extension Manager, which loads very slowly)