My math ended up being right, but I wasn't quite sure for a while.
The wife was feeling a little guilty about getting a new ipad for christmas and me getting a few sweaters (for the record I didn't feel bad at all, I love the sweaters she got me) and we ended up talking about getting a new tv again. The mount we already have is good up to 60", so that's what we checked out while we were killing time between some downtown appointments yesterday.
That time-killing ended up costing me 5" of diagonal space as she convinced me 60" was just too big for our current space, and that a 55" that costs significantly less would be a better choice. So doing some research I found a solid price on the LG above, and ended up picking it up today. It had to be a solo trip for obvious reasons, but things fit just about perfectly and now the box is in our bedroom ready to be put on the wall. I have a feeling I'll put it on the wall tonite just in time to see the Bears get killed tomorrow. Totally worth it.
Current beer-scale: a very happy 7.1