The Odin is a great reg. It is a workhorse and one that I prefer. One question first though. Have you tried one to make sure you like it. For me, the side venting was important, but you may or may not like that feature. The Odin has some "charming" characteristics that you need to be aware of and need to experience before buying to make sure they don't drive you stir-crazy. The Odin tends to have a very mechanical feel (sometimes fluttery) above 30-40 feet. That will most likely be the deciding factor, as it either turns people off the reg, or they don't mind it. In deep, cold water, the odin is great.
A couple things about servicing. Around the great lakes area, I can't see servicing being a problem, as there are a number of posiedon divers in the area. Mexico on the other hand could be a problem.....not sure. You do need a good poseidon tech to properly keep the reg in tune. I have never had a problem with this, but have never tried to get mine serviced down south. If you have other posiedon divers in your area, talk to them about it.
I would advise putting an anti-freeze/environmental kit on the first stage if you are thinking about early spring/winter diving. I'm not sure if there are different kits available, but the one I use is a large rubber cap on the first stage, filled with silicone oil (or ethanol). The design looks very vulnerable to damage compared to those on my Mares 1 stages, but in two years, it hasn't been compromised.....
Bottom line....Absolutely try an odin at varying depths and conditions BEFORE you buy. If you like the feel and characteristics of the reg, then you will be getting an excellent reg.....
Any other questions etc, let me know (email or board) and I'll see if I can help you out further.
Bio guy