We're in the same region. In case you didn't know, RMATS split off from DU and is now WATS (Western Academic Talent Search). Their umbrella organization is now called the Center for Bright Kids (CBK).
In re to your original question, though, it is my understanding that you can use the scores from any talent search program to apply for summer programs with the other programs assuming that it is a test the other program accepts for that grade level. For instance RMATS/WATS uses the EXPLORE for 3rd-6th graders and SAT or ACT for 6th-9th. Other talent searches use the SCAT for the younger age group and will not take scores from the EXPLORE. Also, my eldest took the SAT through RMATS last year as a 6th grader, but could not use those scores for out of state summer programs b/c their talent search organizations didn't use SAT scores until 7th grade. (Not that we could have afforded any summer programs last summer anyway...)
