The only problem with my 40x40 using EBM-PAPST fancap is that on UM2 it will hit the sidepanels. But IMO they are the best for UMO/UMO+ frame.
For UM2 I would use the Gudo fancap that uses thin 30mm blower fans 12v in Serial
It uses BFB03512HHA-AF00 fans, they move less air than the EBM-PAPST but they move more than the um2 fans (that's easy to achieve since um2 fans are quite weak IMO). The main advantage also is that they are blowers, so they can focus air quite fast, but they move less air, so they are good for sma