Hi John,
I'm not trying to stick my nose in here too much, but I was curious about a few things that you may or may not have researched already?
Most of the dive expeditions that I'm familiar with in Antartica REQUIRE that you dive in a dry suit, but also have AT LEAST 20 dives with it prior to your trip. I think this is sound advice, especially sicne you may encounter changing environmental conditions.
I have taught ice diving each year for over 8 years now and regularly dive in water less than 38 deg F all year. There are many different ways to prepare your regulators and other equipment for that kind of extreme diving experience. Take at least one ice diving course and do as much cold water diving as possible prior to this kind of trip. Even if the learning experience requires you to do some short travel weekends to reach those areas, it would be worth it. Freezing, 33-34 degF fresh water places more stress on the performance of your equipment than 28-30 deg salt water because of the salinity factor. It should be easy to explore that learning curve without too much effort.
If you don't dive with a full-face mask, don't bring it. Watching those who have to pull off a full face to switch regs is a nightmare - talk about shock and blindness. If you are determined to wear a FF mask, its best to know it well, and practice wearing your spare mask around your neck in the event of a big problem. For all the years I've been cold water and ice diving (quite a lot of those dives) I've never needed a FF mask. Your face will adjust after that first minute or so of what the? stinging. Your lips wont freeze, the collagen in them prevents that. There are some face coverings you can bring that may help if you have sensitive facial skin, etc.
Cold water/Ice Regulators, lets say not all regulators are the same. Feel free to PM me if you wish my opinion on which brands I have seen offer the less issues. If you are not a regulator repair expert, you better have two regulators with you. If you are experiencing problems or freeze ups, its better to change out the regulator than create clouds of bubbles disturbing not only your diving experience and safety, but the other divers there as well.
I'm coming across a little negative (not my real intent) but most of the Antartic trips have cost about $10,000 US, if you had any problems I'd help you in an instant on the trip. But don't show up unprepared and without any good cold/ice experience, I'd be pretty upset I spent all that money and you might be shortening mine or other people's dive experiences or safety. Let's not go there, take the time to get some good experience and equipment. This is extreme diving.
Have a ton of fun! It is an amazing experience and one which you will not regret.
At the very least you can say you went to the bottom of the world -how many of your friends have been to Antartica?