Speaking in broad terms...

Unless you are really serious about jumping on the ACMI program. Absolutely have the burning desire to fly for what basically amounts to a sub-contractor, there should be, in this day and age, no reason or need to put your credentials on the line, potentially putting a high dollar career with a major airline at risk by accepting a position with a service provider airline.

Even if it's just to try it out, you may pink slip the program or get yourself violated on the line and jeopardize your potential going forward.

Buyer beware!