Are you crazy?
When did TPIC get the back seat to SIC time in at a regional?
Lets see.
1. Pay cut...50% is a lot, and whats your raise going to be if/when you upgrade to PIC at your current gig?
2. Very unpredictable, lets say you go to a 121 regional. What then several years of making less money, and only having the 'hope' that something will move upward.
3. my personal thought (which could mean nothing). I think in a few years, majors are going to be scrabbling left and right for 1000 pic of anything. But I could be wrong.
Good luck in your choicce, but I know what I would do in your situation.