Oops, sorry, missed the kegging comment. In that case, I'd certainly consider keg hopping, but it's worth trying both to see which you like. Keg hopping is usually fine for longer periods because you're keeping the beer at 40f or so instead of 70f so extended contact isn't really a concern. I've left hops in the keg for the life of the brew (a month or so) and never noted any grassy flavors.