We filed EB1A PP by ourselves to TSC last week, and get approved within days together with 485s. Our case is just a little bit above average level.
Currently PP is a good option for you to consider in TSC, personally I believe. However no one knows what will happen two week later.
It looks similar cases are more difficult to get approved in more notorious NSC.
You can file PP by yourself for EB1A, but not EB1B.
Good luck!
