Just to answer officially (rather than pm's -- thanks for waking me up...didn't see this thread!
), no -- haven't done this one, but have heard some favorable comments here and there from local riders who do centuries.
Should be hot in June, but still fairly nice if you get an early start (you know the Valley oven...).
I'm thinking BikeGoddess may have done this one -- might be wrong though. She's done the McLane (now the MERCO Credit Union Foothill century, fyi) century here in Merced in the past, so she may have done Modesto's.
Hope this helps...
~kim
"Only two things are infinite, the universe and human stupidity, and I'm not sure about the former." --Albert Einstein