However, the scary part is Seductress do attack you back for a big 3 damage,
which makes one thinks whether its worth it to put Seductress into his deck.
Three damage is not that big. The only reason that certain three attack cards (like Horned Frog) are popular is because the Adrenaline combo (or in the frog's case, its nice attack:cost ratio).
Or maybe because some have nice abilities and ish.
Three is not big. And considering that the Seductress only needs to seduce a creature with at least 2 attack to make up for it, it's perfectly fine and viable.
What happens if you PU it? Will it continue to stay on the opponent's side? What if your opponent PUs it? Same with using Mitosis.