It's way better than being a generic line pilot... once you have the time, more boxes to check, shows they trust not only your technical skills but also your leadership/organization abilities.

In your case, you're a bit low on TT and TPIC. I would have some angst taking time off from the line in your shoes. But 121 LCA/SIM/CP is very good ticket to punch, and the opportunities are rare. I would hesitate to turn it down. The decision would be influenced by how much line flying I would still do as a SIM guy (I knew guys who never flew the line for months on end in the regionals).