Audio Research versus McIntosh tube amps: anyone experience or compare both?

Maybe try an ARC VS110 or VS115. Not an ARC reference level amp, but might have that warmth you are looking for while still retaining that ARC sound. Uses 8 6550 tubes and easy to bias. I also agree with the Ayre recommendation. I moved from the VS110 to a Theta Dreadnaught II (which like Ayre is a zero feedback Charlie Hansen design) and the bass drive is fantastic with very detailed mids. The Theta also has 225 watts/450 watts into 8/4 ohms vs the ARC rated at 110 watts. Both the VS110 and the Theta are available for around $2,500. 

Used ARC REF150se sometimes trade for $6,000 or less, if you need more watts.  I own one.  Great amp.  I think undervalued on the used market, but that's the market.

Are the fans audible in the newer bigger ARC amps like the 150?
 

Also, is the biasing procedure complex?

Convenience has value IMO.

I have mine on low (3 available speeds) and can't hear them.  Things seem to stay cool enough.  Might need a higher speed if your room is hot, but them you wouldn't want the amp on for super long anyway. 

Biasing is pretty easy.  I think the VT100 is known to be one or the worst ARC amp to bias.

It's a pretty great amp.  I considered replacing it with a REF160S, but they are quite heavy (close to 100 lbs?) and I suspected the 160S will be replaced or augmented with a new amp that uses the KT170 tubes.  I think I am correct about this, as the 320M became the new 330M with KT170 tubes.

The contemporary Audio Research Reference and VT amps have audio biasing and soft start. So, no fiddling is ever needed.