3 pin fan connectors in place of 4 pin molex?

[jtf2]

i presently use a couple sunbeam 4 port mini bay bus adapters to route wiring that end in molex connectors.
#1 holds say 1 6 channel fan controller,and a couple other 12 volt molex connectors
#2 holds 2x pumps and a couple 12 volt molex connectors.
i have found these new little wiring adapters,that use 3 pin fan connectors,and they can be powered by either a molex or a 6 pin pci-e connector


my question then is this
are the little 3 pin connectors too weak to use as the end connector on a ddc pump,and as well as a fan controller-again instead of a molex.
wire guage would stay the same,other than the smaller guage coming off the 3 pin itself

i am looking at these little wiring adapters as they are small,and i could straight run from the pci-e connectors on the psu instead of having to add on a molex to said pci-e connector