This guy did some testing of Monsta and UT60 but seems to be mainly single layer of fans only. There doesn't seem to be a comparison with both in push pull bit I suspect the Monsta may show a very slight advantage with 2 layers. Not with 1 layer.
If the choice due to space is Monsta with 1 layer and UT60 with 2 the UT60 is a clear winner. Its the same story with thinner rads too. Push/pull will always be better than a thicker rad ... especially in a closed case environment where the extra pressure of 2 fan layers increases overall air flow in and out of the system.
Whether that difference is worth the added cost of the fans is a personal choice. It seems to me the added cost and space usage of the Monsta over the UT60 is not really worth it though.
http://www.xtremesystems.org/forums/showthread.php?287200-Flower-Labs-News-Comparison-of-Radiator-Cooling-EfficiencyEdited by Jakusonfire - 10/12/13 at 4:12am