IMHO, when someone sees a ".com" name anywhere, they immediately think "website" (or domain). Take your two examples, write each one of them on a car or at the bottom of a poster or leaflet: Everybody pretty much knows what the .com is about and they may try to enter it into their browser. It won't be as clear for a lot of people with another extension, especially one not very well known (.band is probably not very good on that front). You may mitigate this a bit by adding "http://" in front of the address and/or "www", but a .com is always very recognizable directly.
And by having another extension, people need to remember the extension on top of the name if it's not for an immediate use (or if they want to come back later bu remembering the url).
The .com is usually really better. Now, it's a tough decision between a great name (short / EMD) with an alternative extension and a slightly modified one on .com. If you manage to find a good modification for the .com, that would be great.
Not all alternative extensions are the same (a .net stays quite good).
Maybe it is quite acceptable to use a .band for an actual band, I'm not sure. Doesn't change the "recognizable" problem.