Don't forget, integrating Runes costs POW. You quickly drop in magical potential by having to many. The previw of Divine magic didn't mention Pow loss (I may be wrong, yawn :wink
I tended to think if Rune integration as a special little ceremony to add a rune to your "medicine bundle". Then later, spell are mini ceremonies to call thier powers, using the bundle or other focii perhaps, but if you're not carrying your bundle you loose the powers. A very shamanic sounding system. Lots of RW people carry sentimental knick-knacks, why not runes? You are directly using fragments of godhood to forge magic, how cool is that.
While I haven't seen the companion, just the previws, our current house rule looks like that cults can use cult rune magic without needing runes, but on a one use basis. This is cool because it makes initiates dependant on cults for magic, hence strong comunities for worship form, and it makes divine magic cheap & ubiquitous.
Integrating runes is more difficult & expensive, since it occurs without the aid of supernatural entities, but also grants wider powers. That's the kind of things adventurers do, to become more self reliant, become Heroes.