Can you comment on the time difference? Using the code below, my computer takes 13 seconds to get a billion random numbers using RANUNI and it takes 21 seconds to do the same thing with RAND. If the period is small enough and the difference in "statistical properties" is small enough, I'd prefer the function that takes less time.

data _null_;
do i=1 to 1e9;
x=ranuni(0);
end;
run;

data _null_;
do i=1 to 1e9;
x=rand('uniform');
end;
run;