Unless you have the funds to continue hour building on the twins, or you have a realistic and imminent employment opportunity requiring a twin rating, I would save the cash and use it to build your SEP hours and experience to a useful level, as well as paying for any additional ratings. Presumably you intend to move onto completing the ATPL at some point, which may well open up a number of additional opportunities and then it would be worth maintaining a twin rating, but not before.
As far as workload is concerned, flying a light twin is not massively more difficult than a single. If you are at the standard where you are ready for a CPL skills test, then adjusting to a twin in terms of general handling and assymetric work should not take more than a few trips. The difficulty comes with the additional speed, which will quickly overload you if you are not planning far enough ahead. I would avoid this extra and unneccesary pressure unless you are extremely confident that you are more than ready for the test in a single.
Otherwise, good luck and happy job hunting.
