Excellent info, and thanks for taking the time to write this!
Yeah, had wanted the 6700 because its 140 wpc equals that of my AVR-X5200W. I was wanting to drive my center speaker with the AVR, if possible. Some people claim that their center speaker sounds more impressive with a higher wattage amplifier. And I did like that the 6700, like my 5200, is made in Japan.
But I'm told here that that the 125 wpc of the 4700/4500 is plenty of power for my setup. I sit ~10 feet from the speakers and my center speaker's sensitivity is rated at 88dB, and I don't really listen that loud.
I'm very interested in a pre-amp mode for my front L/R speakers, as I drive them with a Krell amplifier. BTW, its input sensitivity is 2.7Vrms, and it has 26.4dB of gain. Although I intended to drive the center speaker with the AVR, I do have an amp that I could use to drive the center speaker, if I can find room to place it.
Based on the comments of you and others here, it does not appear that I can justify paying some $1,300 more to get the 6700. As to 4500 vs 4700, it seems that the 4700 would be a better choice for me, because I want to do the preamp mode for at least the front L/R channels. I assume that if I buy a new 4700 at this point, it will have the downgraded DAC, but I don't know I would be able to hear any difference, given my moderate listening levels.
As to the 4700, Best Buy has it now for $149 off, and I have $155 in BB rewards, so it would be about $300 off. My reward points start expiring on Oct. 29, so I need to make a decision soon. As to the 4700 for sale on ASR, I would assume there would be no warranty, but that is a great price.