IME, the right amount of offset varies with the recording and the level you're listening. I've found it's rather tiresome to try to improve the overall SQ, but here's what I've done.
To deal with the somewhat complex situation of tweaking bass and surrounds differentially that you mention, I've tried a few permutations, all of which are pure preference-so YMMV.
The best but most complex solution IMO is to use DEQ with the offset set to where I want it for bass, then use the fader (ch level button on remote pulls up OSD) to turn down the surrounds. Remember to reset the ch trims when done.
Sometimes I skip DEQ entirely and just use the tone control to increase bass. Remember to turn Tone Control off when done, or when you have the same source and mode playing, and don't turn on DEQ, the 4311 will apply that bass tone setting.
Sometimes I skip DEQ entirely and simply increase sub ch trims for more bass. Remember to turn them back down when done.
Sometimes I use the fader to trim up or down surrounds regardless of whether DEQ is on.
But generally speaking when doing serious listening to well recorded material (and that's pretty much what I do ) I just turn it up till it sounds really good but not too loud. That's usually around 75-80dB. No EQ tweaks to set and thus no EQ tweaks to unset.