Very good points raised here.
I whole heatedly second the suggestion to invest more in speakers than electronics. This is a timeless principle every AV enthusiast should make a life motto

.
The lack of objective comparisons between manufacturer flavors of auto room eq leaves the whole matter subject to opinion or speculation and mostly, subjective compassion by someone switching brands. Indeed, some folks swear off it altogether, preferring an eq free sound.
Yamaha and Denon does seem to have a better track record with QC than Onkyo. That said, a lot of folks underestimate the amount of heat a receiver can put out. I frequently hear about receiver malfunctions that can eventually be attributed to speaker wire shorts and insufficient ventilation.
To be honest, the Denon X4000 may be overkill if you won't use the features like 3 Zones, pre-outs and dual sub, networking, etc. Pick the receiver with the most features you actually see yourself using.