I just got back from a 3 day visit to DLR. To me and my group, it didn't seem like there were all that many CM's trading. The first day (6/18), I think I traded 3 pins. The 2nd day, I didn't even bring my pins. Got a bit more focused on the 3rd day and found more CM's. We did take advantage of the Haunted House O-pin event happening now until sometime in August - got some limited additions, plus lots of other pins and stuff.
I was at WDW this past December where I really got hooked...seemed like there is much more participation in FL. My experience in FL with the non-CM's (those with the books) are that the never want anything you have, but if you want one of theirs, they'll gladly show you a $14 pin to purchase. If you aren't a serious collector - beware - you may be "trading" for a scrapper they got off ebay for $1.25. It's much funner to trade with CM's anyway.