I hate to break it to you, but you can forget the 16x burn speed. Using 16x media in a recorder is like putting leaded gasoline into a BMW: gas is gas, and it may run a few miles on it, but you'll regret it soon enough. And none of these recorders even approaches 16x burn speed, on average they hit 8x if you're really lucky. The Panasonics probably have the most up-to-date burners of all current recorders, but they're still proprietary weird recorder burners instead of generic PC burners. If you want repeatable, reliable long-term results with a recorder skip the cheesy 16x pc media and get the premium 8x TY or Verbatim online. The cost is not that much more, it saves a huge amount of stress on the recorder, and increases your odds of consistently faster burning.
Regarding the 220/240 issue, US import dealers are not usually interested in selling things that can't be used at all in the US. Next unit you get, try plugging it in (before returning it) to check if it auto-adjusts to voltage (most global-market models do this even if labeled 220/240 only). Dealer sales staff and order takers are beyond clueless about the standard items they sell, forget the exotic stuff like an EH69. I went to J&R in person three times last fall to buy American-market Magnavox recorders, and each time the sales people had no idea how to even write it up, couldn't find it in their stock system/sales terminals, even though theres a display model and stacks of them for sale right under their noses. It isn't only consumers who have no head for DVD recorders, the sellers are even less informed: you have to hold their hands. Thats why it pays to buy from a place with a return policy: you really do have to buy 'em first to see how they'll work for you. The stores can't tell you anything useful and mfr info is hopelessly cryptic.