I think 4/4 is fine, since it's very close to vanilla. If you make it uncommon, you could pretty easily make it a 5/5 (and 3GG)
Remember that we don't necessarily want these to get picked first. They are much more powerful in multiples, so not being as powerful makes them (somehow) better. We need the cards to be mediocre so they can shine if you are able to draft multiples.