Which AVR to purchase

Of course, you are forgoing all the newest DSP room correction technology (knowing that the deficiencies in your room acoustics are likely pulling the sonic integrity - and potential - down, likely) with these otherwise good sounding receivers.
That said, it's hard to beat the Arcam, as a tool, by-itself. It's got good refinement of detail, good balance of warmth and clarity, and quite sounding.
However, better power, body, weight, impact, transient response, etc, can be had with a modest newer tech receiver with 1.3a HD codecs and an outboard amp - not to mention the lastest in acoustics friendly processing.
But besides all that, considering reliability issues in past with NAD, I like the Arcam here. That and I can't see any receiver blowing the world away with sonic magic, so I don't even need to consider the Cambridge.

I've tried the NAD, Arcam, and now have a Cambridge. You can't go wrong with any of them. I'm very happy with the Cambridge.

See you can pick any of them and expect about the same "realm" of performance. My experience says Arcam has a better track record of maintainability than the NAD, if that helps. Cambridge, can't tell ya.
Wait, doesn't cambridge make entry level speakers and such?

ARCAM is what I would consider, however, I am holding off on the AVR350 and leaning toward the DENON AVR4308CI for the time being due to "Next Gen" line-up....

I agree with Iplaynaked (he plays Canasta). I just replaced my Sony CRT and DVD, Integra 6.1 receiver with a Blue Ray, HDMI, True HD, self calibrating reciever, and compatible components. The improvements in both audio, video, and switching are simply stunning.

I gave up on getting this HT to image like my two channel and resigned to enjoying video/music and music/video's. Spend your money on decent and sensitive speakers and an up to date receiver and player.

Here's another thought, along the lines I mentioned.
You could buy something like a newer Harmon Kardon (Stereo Dave's in Oregon Mod's these, also) AVR 247/347, with DCI Faroudja processing, 1.3a HDMI and Dolby HD and DTS Master, 1080p vid switching, EZset Parametric EQ (tune out the nasty peaks in your room), same 100db sig/noise specs as the Arcam,
multi-channel inputs, and and overall superb sound quality in an otherwise budget receiver line!
Actually, the tonal qualities, clarity, detail, and lack of coloration (even similar warmth range - although the HK is a tick warmer, if better balance I think) of these stellar sounding little Av receivers is superb! I think the best around for mass manufactured AV receivers, personally.
You could then spend a few hundred bucks buying one of these, and add a superior set of amplification with a used mult-channel amp! (which, BTW, will stomp the amps in any receiver with careful selection. Plus less electro-magnetic interference, less noise in the sytsem, better dynamic range, etc). Not to mention, yes, you can get these moded for even more refined sound!
Anyway, it's a consideration to your all-in-one solution, with older technology you're considering.
Personally, I wouldn't consider any of the older receivers, with no current tech EQ, no HDMI 1.3a, no HD codecs, No 1080p vid(???), and limited power, ideally, etc.
Maybe this helps, maybe it doesn't. But it's more info to toss around

You buy an Arcam make sure it was MADE AFTER March 2008, because we are replacing 100% of motherboards for units made before then due to overheating. Have 13 Arcam AVR2XXX-3XXX units in my warehouse waiting new motherboards since Sept. and customers are ticked to say the least.

Buy a used AVR 2XX-3XX and need the motherboard you are looking at $500-$700 in repairs. No Arcam warranty is transferrable, buyer beware.

NAD (we're warranty Authorized NAD, McIntosh, ARCAM, Nagra and Plinius) never seems to overheat, and you get 95% of the sound of Arcam for 1/3 the price and 10X the reliability (over the older Arcam).

Take care