saslpasswd2.exe included with Subversion 1.6.15 does not generate a sasldb nor does a previously generated sasldb work with the svnserve.exe service running. I reverted to 1.6.13-r10002845 and saslpasswd2.exe was able to sucessfully generate sasldb and previously generated sasldb worked with svnserve.exe service.
saslpasswd2.exe -v on both version state Built against SASL API version 2.1.23 LibSasl version 2.1.23 by "Cyrus SASL" regards, Coleman