I'm looking for a CX or 'gravel' bike to supplement my road (Cervelo RS) and little-used hybrid (C'dale Quick).

Application: some light trail (e.g., packed gravel path, hard dirt), some weather (it does snow here, it'd be nice to be able to get some outside miles in). For dry paved rides, I'll chose the Cervelo. Otherwise, probably this bike. Room for "Fat" tires (>35) necessary.

I'm not a CX racer, I don't need the top-of-the-top-tube cabling, and am unafraid of cable that go down the downtube & under the BB.

Desires: Disc brakes. I'll build the wheels. Similar riding position & handling characteristics as my Cervelo (2011 RS, sz 51). I'd like to build it myself, if feasible, though I understand that this may be significantly more expensive than buying something complete and upgrading where necessary. (One learns a lot about the bike by having it in pieces in one's hand, vs. just looking at it & upgrading where desired).

I'm weak, I'd prefer something not too, too heavy (but realize that it may be quite expensive to get near to my ~18lb Cervelo, which isn't the goal).

If possible, something durable or inexpensive enough that I'm not going to be afraid to take it out.

Friends continue to try to talk me into an Ibis Hakkalugi, but that may be more expensive than I want to deal with. (At the same time, it may not be too expensive

Thoughts?