Well, as long as you don't lose the dragons (since you can't resurrect them), they'll be a fine addition.
The Royal Griffins are great, but they need some items and some complementing units to help them shine. For example, some items with + physical resistance will help greatly. Then, some items with fire resistance will help, because they have -10% base. Finally, target + Stone skin + magic shield from the archmagi and you're ready to use them properly
