I also doubt that players can downmix the rears. I don't know any better, but I'm quite sure they can't matrix from 5.1 to 7.1, or other post-processing, so...
I also vote for the 55 if m-ch analogs are a must.
I'm sure you'll find your solution Sheep, but FWIW, I usually recommend to others in getting the BD35, and taking that ~/+ $100 towards a new pre/receiver sometime later.
First of all, there are a number of folks who tried analogs, and ended up getting the new receiver, anyways.
I used SPDIF for a few months until I changed out my NAD for an Onkyo. Many, or actually most, or perhaps almost all of your legacy/core streams will have increased max bitrates via SPDIF, compared to DVD. Just my 2 cents. Depends on the budget of course.
And EJD posted that $199 deal, I think it was, on the BD35. w/ 6ft HDMI cable, whoopdie-doo.