The new 3406D MSO is really expensive. The old 3406 MSO is limited with those 500MS/s but still a good product at that price point. Also the software has all the functions available for the new models (free CAN decoding, segmented memory, etc).
It's not going to replace my good old TEK TDS7104. I'm going to use it as a logic analyzer and portable isolated scope (with a laptop). Also I think it can be really useful as a data-logger.