With Ryzen memory latencies are a bit larger than what is seen on Intel, so timings could have an effect on things. It is something that will need to be tested in the future.
There is a reason why the last AGESA update focused on lowering memory latencies.
I will include a table from Crucial below to help explain that memory latency is more than just CAS latency. IE, clocks and CAS timings are a factor.
http://www.crucial.com/usa/en/memory-performance-speed-latency
With Ryzen's natural memory latency being a little higher than Intel's, AMD could potentially benefit from memory with tighter CAS timings, though as always this will benefit select scenarios only.
This is something that will require dedicated testing in the future.