New beta autoexec for 4.0.0: https://github.com/mastercoms/tf2cfg/blob/4.0.0/mastercoms/cfg/autoexec.cfg
Has improved organization and comments, as well as better defaults and options.
I'm working on new presets for 4.0.0: maxframes, competitive and maxquality.
I don't know if I should make a lowend/potato/toaster preset because usually what ends up happening is some people think lowend = fast and then use it on their modern/powerful PCs. Besides, there are a lot of variations in accomodating different lowend PCs that probably can't be accounted for in just one preset, so I think it is just better to refer to the documentation to determine the best settings for your PC in that case.
There have been a few controversial defaults in the config as well. Most of you may have had problems with host_thread_mode 1 and wonder why I have it as default when it has issues on local servers. My reasoning is that people will notice their local server games not working and will be reminded to change to host_thread_mode 0, while if it is host_thread_mode 0 by default, there is no reminder to use 1 on multiplayer games for people who do not read the documentation. Of course, I'm here to provide a good config for the community so if most of you prefer host_thread_mode 0, I'll change the default.