Yuppers the SR-1 is designed for lower RPM fans...
I've owned the RX360 which is pretty much designed the same way..
I have used gentle typhoon 1150 RPM's on them and they performed fine while being extremly quiet.
Here is a link for a radiator comparison..
Skinnee Labs | Triple Radiator Comparison V2
based on the average 10 degree delta chart you can tell that the SR'1 starts losing it's thermal performance againts other radiators at the 1450 RPM mark and above.
P.S. I recently upgraded to the TFC xchanger and am using the Gentle Typhoon 1850's over my 1150's. and there is a noticble sound difference... theres this weird clicking noise but I have gotten use to it.. I am now I am hearing more of the air being pushed..