If the FTO delivers a JOC in an FNPTII, then it is a very inexpensive way to get a block of hours. The question is whether or not you need the hours. If you did your MCC in a Jet simulator, then you probably don't need it. If you did your MCC in a TP simulator, a JOC could be a good way to get some Jet sim time on the cheap (I might wonder why you'd do an MCC in a TP though if you're going for jets). Having a JOC might raise the expectations at a sim check, but it also could help you do better in that sim check. It's a tough call and I think it would be difficult to decide without knowing a bit about the requirements of any particular airline you might get a simulator check with. The problem with this logic is that you might not have enough time to cram in a JOC if you get the call for a jet sim assessment.