Hi Dan,
I read through the Equitech paper, and it strikes me as excellent. However, it also strikes me as not inconsistent with the comments on balanced power in the Jensen paper, which is to say that there would probably be significant hum reduction if you used a balanced power arrangement, but not necessarily a reduction that is fully satisfactory.
From the Jensen paper:
It is also very unlikely that the two capacitances, CPS1 and CPS2 or CPS3 and CPS4, would be exactly matched in any piece of equipment. Mismatch ratios of two to one are common.... Although intuitively attractive, [the balanced power] approach can completely cancel interchassis currents in a system of three or more devices only in the case where each of the devices had such matched capacitances. This would be an extremely rare occurrence.... 10 to 15 dB hum reductions ... would be more routinely achieved.
From the Equitech paper:
If any aspect of the circuit is applied OR LOADED [emphasis added] in an unbalanced manner, noise will appear in the ground.... On the average, 16dB improvement in background noise has been noted.
In other words, any difference between the stray capacitances CPS3 and CPS4 in your particular amplifiers (which is unpredictable) will limit the amount of hum reduction balanced power would provide.
In considering the 10 to 16 db numbers, keep in mind the rule of thumb that a reduction of 10db is subjectively "half as loud."
Best regards,
-- Al