When we lived in cold country I did both (because I'm a belt & suspenders kind of guy). I'd blow it out with 30 psi and leave the valves open to the hot water tank so that it would blow out as well. Then I'd reconfigure and do the pink antifreeze (more than 2, but less than 3 gallons).
One can't be too careful.
Ed & Bev Felker
Retired USAF Col and retired Nurse
Traveling with Lily & Bella ('Teddy Bear' breed)
2015 Vegas 24.1 (E-350)