You will learn a lot more in the left seat of a TP than you will doing more of what you already do. Command is enjoyable, TP command is a blast but harder work than right seat jet. Only you can answer the question and to come up with a sensible answer you need to clearly define your own priorities. The risk of left seat TP is that generally there are fewer job opportunities from reputable employers compared to narrowbody jets.
If I was happy with employer and didn't foresee a risk of redundancy in the TP and had prospects of moving back onto a jet in the left seat without having to wait more than 7 or 8 years I would definitely take the command.
If I was thinking of moving company, was unsure about the company finances or could be stuck for 30 years on the TP I would be a bit more cautious.