F5 GTM vs Cisco GSS

Yes right now I have Round Robin for Preferred and Alt method (RR/Return to DNS - ALT). Also in the past when I've tried drop for fallback method but surprisingly or unfortunately ran into a bug (which threw our F5 support off balance) that GTM response all pool members with random TTL time and we ended up with several production issues with lots of user connections to DR servers, or server with lower order...I tried preferred to Global Availability but ran into issues while setting DR setup and also if order is not properly defined (which somehow our deployment engineer always confuses/forgets to add it properly) the GTM query reply are not as expected but as configured.