I currently have none - sold my 770 about a year ago, and a pickpocket in Stockholm got the N810 last month. On the upside, that made one decision easy for me; I'll be buying the new NIT as soon as it's available.

As for memory, I'm happy with microSD(HC), as I've switched my camera and audio recorder over to microSDHC - 8G in the camera and 16G in the recorder. The adapter stays in the camera, and the card is quick to swap. For my purposes, it's a great solution.