I guess the Sharp is the only model offered to you. If buying it I would give some attention that C/NET said it has less than average standard definition performance. That is perhaps an annoyance you would find frustrating as an ongoing factor. The relative lack of a bit of blackness is something I could better accept.

My opinion is to not be much concerned whether you are getting 5.1 or 7.1 Yes, surround fans may stress more is better. I don't feel the relative difference is very important. Apparently you want the convenience of an HTIB. The Onkyo model you cite is a pretty darn good one. C/NET has given it good reviews.

When it comes to the furniture involved, it is frustrating that the seem so expensive. I confess the one I deliberately got because of fine style was, indeed, more expensive than the IKEA you cite.

Combining normal living space to accommodate speaker placement nearly always involves compromise. Yes, if 7.1, it would be nice to get the rear surrounds behind the sofa. Your room is apparently pretty generous size. Can you live with the sofa not being up against the wall?

I never accumulated enough air miles to get any return on them other than a bunch of magazine subscriptions. I realize the situation of those who fly almost constantly is different.