To be fair, this really isn't a "deco dive" even if your computer indicates it. For it to be a deco dive, there would have to be at least one mandatory deco stop on the way up. At the Blue Hole, you have a fast decent down to 140. Quite often a computer will drop into deco since it's computing nitrogen load in the fast tissue compartments. As you start your diagonal ascent, the tracking will still be on these compartments and they'll off-gas quickly. The computer will then drop out of deco. Since you never really had a mandatory stop, this wasn't a deco dive.
I'm still torn over the Blue Hole. I don't think it's for beginners, but I don't want to scare people off either. It's a majestic, eerie dive. Certainly different than reef and wall diving.
-Charles