You said you are planning to use your system for 70% music, but does that mean 2 channel music or multichannel music? If you intend to use your system for mostly 2 channel music, then as others have said, I think it would be a big mistake to downgrade your front mains to match the center channel. Get the best front mains you can afford and don't worry about voice-matching them to the center channel speaker -- it is a non-issue if you are only using the center channel speaker for movies.
On the other hand, if you are listening to multichannel music (SACD or DVD-A) then the center channel speaker becomes more important, but even in that case, I would not recommend compromising the front mains at all for the sake of matching to the center channel.
That said, I am not so sure about the idea of watching a movie in "phantom center" mode with no center channel speaker. Around 80% of the soundtrack (especially the dialog) is directed to the center channel speaker. Having that speaker close to the video screen ensures that dialog will emanate from the actors' mouths, not from somewhere else.
On the other hand, if you are listening to multichannel music (SACD or DVD-A) then the center channel speaker becomes more important, but even in that case, I would not recommend compromising the front mains at all for the sake of matching to the center channel.
That said, I am not so sure about the idea of watching a movie in "phantom center" mode with no center channel speaker. Around 80% of the soundtrack (especially the dialog) is directed to the center channel speaker. Having that speaker close to the video screen ensures that dialog will emanate from the actors' mouths, not from somewhere else.