yes, with n_val=3 (default) 3 nodes is the minimum. I was merely testing (actually had 3 riak instances on a single box as a "cluster") but with r,w=1 and n_val=1 it was about the same (slow), which was disconcerting. cpu was very high in one instance (others were nearly idle, and IO was low. I did not try dw=0 though (if that would even work). Might be worth a try.
I am going to try bitcask too, to see if eleveldb was the culprit and could be tuned.