can't really comment upon TSSM, never been to them before, however its known throughout high schoolers that TSFX provide great notes that supplement the course material really really well.
So, if your going for notes that summarise the course content in a good manner, go TSFX, however some lectures tend to get a tad long and boring ( depending upon the lecturer you have )
, this is just my personal opinion, however most to all lecturers are well informed and experts in their area of study, and are pretty friendly towards all students are usually always open to questions.
As for TSSM, hopefully someone who has been there can answer that question because i am considering going their for spesh.