So let's take a look at this. Here's some footage from Rockman NEO, the temporary name given to Rockman DASH while it was in development. The footage comes from a VHS given out in Japan with the Capcom Friendly Club, a promotional magazine from Capcom (you can read more about that here). The demo build of Rockman NEO itself was also released, but seems to be pretty rare. Only a couple other of videos of it are on YouTube right now, and have no sound.
There are a fair number of differences here from the final game. These include differences with the model of Mega Man, a different symbol for the weapon gauge, and a significantly different design for the Apple Market. There are also audio differences, such as certain sound effects and the sound samples of certain songs. The theme of the Bonnes also sports a slightly altered melody. To see the game like this makes me really wonder what Legends 3 looks like now!
I must give many thanks to Arasoi and Retro Reality for procuring this footage for us. Though it's a bit soon to announce, there's quite a bit more stuff our sites will be collaborating to bring out in the coming months!