Re:wetsuits drysuits (Score 3, Informative)

channel attempts are very short compared to a transatlantic swim. it's over in a few hours, whereas you're looking at several weeks in this case.
things to keep in mind:

• traditional wetsuits, and especially drysuits are made for diving, not swimming. they are too stiff to swim for more than a few minutes (read: extra effort going nowhere) and cause abrasions / chafing in lots of places (neck and shoulders especially). there are suits made especially for swimming (try Quintana Roo or Ironman Wetsuits), but von Tetzchner is wearing a diving suit.
• you can't stock enough supplies for two people in a rubber inflatable.
• sharks. you'd probably want to swim in a shark cage.
• currents. unless you were totally insane, you'd rather swim with the currents than against them.

by the way, here's a guy who actually did it.