Im in Summerlin and do have trouble with Simulcast. The thing with trunked systems like SNACC is the sites are not linked and users radios automatically connect to the site that offers the best reception. So if you're listening to Apex and someone is on Angel, you may not hear all users. During an In-Flight Emergency (IFE) earlier today at McCarran, I was listening to the ARFF units on TG 2639 via Apex. I noticed I wasn't hearing all the units so I fired up another radio and heard more traffic on Simulcast than I did on Apex.
The same goes for LVMPD and their P25II system. If you're listening to Apex or Sunrise Mtn., you will only hear Bolden, Northeast, Northwest and maybe the Convention Center and Downtown Command Areas. If you want to hear South Central or Enterprise, you should listen to Simulcast, Blue Diamond, or Sloan.
Also, there is an error in the RR database. One of the more active frequencies on Apex 851.4000 is listed as 51.4000 so you will have to go into your radio and change it manually until the database is fixed.