FMC Overheat
It's not a stupid question at all and dependent on many factors. I was told to never turn down a free type rating but that came from a guy with 5 different uniforms in his closet! In most airlines Seniority is everything and a couple of numbers can make a huge difference. Having said that, P1/PIC time can mean the difference between getting or not getting the next job. The best anyone can really say is that it's a crap shoot. Take this example from the past for instance. Join prestigious Pan Am as a second officer and have a job for life or cough up your life savings for the right seat of a clapped-out, foreign-registered BAC1-11 for a start-up out of Luton, that no-one's ever heard of; Ryanair? Who'd have thunk!
Make your best guess after talking to as many people as you can.
Best of Luck
Atlast
PS I've turned down 2 free types. CV240/340/440 because it was attached to a 2 year contract in Laredo,TX and L382 because right seat on the 747 was a no-brainer!