You know i was thinking along the same idea as your set up, before family got my new case and all. I was in process of building external set up. I had allready ordered enheim 1250, res. tygon & i have set of colder disconects. I would like to add disconects to my system but i'm afraid my pump my not handle it (dd4 laing). Colder disconects have a X piece inside valve i thought about drilling that out so as to decrease resistence?
Will be following close so as to see how your set up performs it looks well thought out for 1st. time. With my spare pump & stuff i will set something similiar up.