hmm, i've read the DM book, so i know exactly what it involves, unfortuantly, i'm also a really good swimmer and would get full marks on all the tests. But, i am putting nails into the coffin of your illustrious, experienced diving career. Pay your money, get your qualification, then pay more money every year to keep doing it ;]. DM is a lame qualification, again i repeat, it is a good introduction to people who want to eventually become instructors, which really should know what they are doing before taking this route. Unfortuantly people regularly do DM, because they see it as the next step from rescue diver, which unfortuantly PADI have deemed it to be (i know they dont claim this, they just don't offer anything else)
Wow, grossly misinformed once again. "Reading the DM book" and swimming a few laps does not mean you know what the training involves. I have not made any claims to have an illustrious diving career. I do hope to be an instructor eventually, but want to take my skills a whole lot farther before I do that. But since you know it all, here's a few more reasons why being a DM is not "lame":
1) Crew on a boat = FREE diving. Here in NC, that is going to save you mucho moola on offshore dive trips, will more than pay for your DM dues over and over again
2) Work with a shop = free fills, everything else at cost. Again, if you are a frequent diver or involved in any tech diving, this is huge. Filling a couple of sets of doubles with nitrox every week or two is not cheap.
3) Share your love of diving with new divers. Working with new divers is rewarding, even if you aren't getting paid for it

4) Building your network of divers.