Personally, I feel this is a better setup for 5.1 music than using the rears, because your ears have a lot easier time hearing stuff to the side than behind you. But obviously, ymmv...

The way I currently have my 6.1 setup (and the scheduled location for re-hanging the 6th when 7th is finally hung) I agree. The best surround for 5.1 will be using the side surrounds in my application, and all rooms to date I’ve listened in which are currently rigged for 7.1. I would personally choose the side locations to implement 5.1 tracked music.

Some have trouble with the acoustical playfulness of some mix's and inconsistencies in how information is repeated or seperated into the 5 tracks offered in current SACD and DVD-A's on the shelf. Many have commented on being startled by a single instrument which would normally be showcased in a recording at FL or FR of the soundstage, popping out distinctly in multichannel all around them or some have commented they just can’t get used to hearing guitars come from behind. Using the farthest behind the ears location of speakers hung in a 7.1 configuration bypassing SL and SR would I think tend to exacerbate the situation for those whom this annoys, especially the 2-channel purists who are attracted by the high-resolution but not to sure of the value of the format. And since we don’t listen to ‘live’ orchestration in the round, I would think the S surround’s are the best choice for locating a multichannel surround performance of music.

I do love however hearing a bullet travel from behind the good guys back (when his back is shown to me) traveling up to the center speaker and out into the distance. Its realistic to how I would hear it if a sniper fired from behind, very fun.