Actually the Dr. Laura and Rush delays on WSML were due to the WPTF contract which had included Alamance County. Once CC owned WSJS/WSML, they put the pressure on Curtis to drop the county. It actually came down to a cancellation letter for WPTF. Whole deal was redone and WSJS was clear to institute the full simulcast.
WSML was added to fill Guilford holes in the WSJS directional signal. Nights didn't really matter much.
It has always been hard to tell the impact of WSML in the ratings, since the only use of those calls come in the legal ID at the top of the hour. It is generally accepted within that any Alamance diaries are actually reporting the 1200 signal, but entries use the WSJS calls.
I have always heard WSML could be upgraded to 50KW day, but would have to be directional. There was a time we thought it would happen. There would even be some nighttime increase. WSML shares the frequency with WOAI (Clear Channel's flagship in San Antonio). Once the station was sold to CBS it was unlikely that WOAI would agree to accept any interference from WSML.