Renting your card out is a good solution if you can't use it at full power in your line up. You will have the same card from your spell book if you have level 1 summoners. So you don't need it and it can bring you in some nice rewards that you can use to buy other cards. In addition rented cards continue to count for your points for the sps airdrop! The other thing that you might want to consider is that Gold foil cards bring 500 points that you might need later to get up in the levels. But here again, the decision is easy. You just stop the renting and the cards counts on your own points when you need it.
RE: To Rent or Not To Rent - Depends ?