The problem you will run into is that you will have to drop one of your two professions to take up JC. If you drop mining (assuming that is what you coupled with engineering) then you will have to buy your JC mats on the AH = expensive. If you drop Engineering, all those goodies you are wearing will suddenly appear in your bag since you do not have the required skill to use them. Ideally you could have taken JC first, built it up and then stocked up on little healy guys, then gone down the engineering route so that you could wear the gear. Overall it is up to you, but this is something to think about.