I have a favorites list which I use in 436s, 536s, and an SDS200, where I managed to get 15k+ RIDs in before I hit the 1MB limit. That system has 300+ sites and a couple thousand talkgroups as well. If you had less sites and/or TGs I bet you could add more.
That system in my FL is now over 20k RIDs known, 2100 TGs, and 340 or so sites, so it's well over 1MB if I try to put it all in.