I'd say it's a gamble on whether or not you think you can get 70's UCAM or DCAM depending on the TPG of your choice. If not for 69's I'm not sure if when selling you'd end up any better than if the coins were raw when deducting the cost of slabbing. Raw and 69's seem to sell for around the same price on Ebay $100+, but 70's are going for roughly 3x that based on recent sales.
IMO, no. If you want one that's graded, buy it already graded. Otherwise, save your grading/shipping to/shipping from fee's as they will only add to the amount you have tied up in the coin.