Is there any obvious advantage for monoblocks?

High power capability, that you can still pick up and carry.
Short speaker wires/long interconnects... probably a wash.
Separation (low crosstalk) is a myth unless your stereo amp is a clunker.

Staging will be a plus with mono-blocs. Separate electrical ground plane. And with the correct coupling platform under them an enhanced mechanical ground to earth. They will then react as two separate amplifiers tied together only thru the same ac outlet and the stereo source. Of course you could have several dedicated ac lines with isolated grounds. That set up makes all better. Tom

Parasound had an amp (HCA 3500 I think) which was so dual mono that it even had 2 power cords and switches. This thing tipped the scales at 85 pounds and begged to be mono blocks at about 44 pounds each. What were they thinking? In these days of everyone using dual transformers, I feel that any new stereo amp that is going to weigh more than 50 pounds or so should be redesigned as mono pairs. If you need to ship a 90 pound amp with a bad channel back to the manufacturer, you'll wish it was a 45 pound mono. Much easier to pack and ship to say nothing of much cheaper.

Cooler operation.

I own a Parasound HCA-3500.Hard to move around, but exceptional bass power and extension, goes to REALLY HIGH VOLUMES without compression or strain, and has great imaging and sounstaging.The bass is its biggest advantage in my situation.I use 2 dedicated 20 amp breakers and 2 seperate lines and outlets for each power cord!!