Glad to see some love for the music on mm6. Probably my favorite up until mm9 came out.
I have the GC version of the MM Anniversary collection. Not only does it have MM 1-6 it also has 7, 8, PB1, and PB2. It has some extra music and art stuff if i remember. But it also has a stupid noob mode and the reverse buttons can take a bit to get used to.
As far as displaying 240p, I was playing on an old sylvania crt at the time so the picture quality was bad all around. I have a GC now but I havent hooked it up for quite some time.