If you're planning to work as a DM train where you plan to work. Otherwise, it's unlikely you'll get an opportunity to even apply for a job as one. I would not consider a DM that trained in the Caribbean in a 3 mil or shorty to help me. You'd need drysuit experience, very cold water (think 36-38 degrees), low vis (2 ft or so) experience, and be able to take over the class at any time in the classroom, pool, or open water. Under supervision, of course.
If you don't plan on actually working as a DM don't waste time and money getting a DM cert. It won't improve your diving or do very much for your diving knowledge. Tech training or a Master Diver program like NAUI and SEI offer will do more than the DM training will do. Both are intended to offer instructor level (and actually more than many OW instructors) knowledge and skills without the teaching component. Plus, you'll not have to shell out money for dues and insurance every year.
I know a "DM" who never bothered to get insured. So so diver, but he was technically never a DM. He just had the card and helped out with a few classes for a shop while an intern. But without the insurance and paying dues, he was never a DM.