You are reading too much into it too. My points are quite simple.Original Post Deleted
1) I don't know how much degredation is due to the OP's walls. But then I doubt you do too
2) A newer router on AC may well out perform the one the OP is using, in his current use case. I'll highlight the word 'may' again.
3) The OP already said he wanted to upgrade to a new router, does not hurt to try both 2.4 and 5.