I don't think the clip on zefal type guards will work that well with big 29er tyres as they will lack clearance and not cover the whole tyre edge on leading to upwards splatter, we use a lot of the clip on's at the project as they are a quick fix upgrade for people wanting guards and while handy they aren't that handy.
You can get very baggy full length guards for Hybrids and MTB's by the likes of SKS or Esge that will take a 2 inch-ish tyre but I would excercise caution with an off road or rough stuff bike if mounting full length guards with stays, avoid anything too rigid (aluminium) and make sure P clips are the mounting point for breakaway secu-clips, not just a direct bolt on mount.
Ah, I probably wasn't all that clear, the clip on mudguards would only be for road use with 700x40 tyres. I was just exploring options, I'm still not clear in my mind yet.
Basically I've now reached my 4 bike stable, custom Ti road and 29er, steel allround commuter with hub gear and fancy dynamo lighting and an old hack for shopping duties. But I'm realising that, now I've got to here, I'm now not so sure here is where I want to be. I instinctively rail against the idea of having bikes that don't get much use, part of the thinking behind the Ti was useability in all conditions. Whereas the steel Vaya is getting all the use and the Ti bikes are more like ornamentation.
So I was trying to decide if I could ditch the Vaya and which of the Ti bikes would be best suited to take over its duties. I think I've come to the conclusion that it's the Ti road not the 29er. It has the same clearances as the Vaya, full rack and guard mounts and is the most likely to be used for night riding, so most deserving of the dynamo lighting. Plus I already use the clip on guards on the road bike and they work well.
So 3BM will be delighted that his prediction of the Vaya coming up for sale is going to come true...just got to decide if I sell as complete or break down to parts...there are some bits I want to keep.