Ask AdamM about the difference between the cross check and the peregrine.
I have a disc fork on mine which worked wonders for stopping quickly both on and off road. Don't mind not having a disc on the back since rear brakes do so much less of the work.
I ran my Cross Check for years with the original fork and cantilever brakes. It developed an interesting shimmy at 35mph with accompanying brake judder which was all rather scary so I ended up buying a Kona P2 700c disc only fork for it (now on my Steamroller) which sorted the problem. However, as Sheldon says, frame shimmy is a function of the bike and the rider so you may not have the same issues.
I loved the Cross Check but for general purpose off road use I wanted disc brakes (to avoid destroying rims quite so quickly) so the Peregrine was the perfect replacement. Also, I'm friends with Sam who owns Singular Cycles so that was a factor.
The Peregrine is essentially the same weight as the Cross Check (possibly slightly heavier due to the EBB?) but I'm not sure exactly because I don't really care. They are very similar to ride as the geometry is very similar indeed so no surprises there. If anything, the Cross Check is slightly more compliant because the fork and stays do not have to be built to cope with the forces associated with disc brakes. Ofsetting that is the much larger tyre clearance on the Peregrine (up to 29x2.0 in front, 29x1.8 in rear).
I am extraordinarily happy with the Peregrine, it's exactly the bike I wanted. I've ridden a few long-ish (60 miles +) road rides on it and, while it's more than capable, it can feel a little 'dead'. But that's a good thing as otherwise it might get a little too interesting if you loaded it up with panniers! Off road is where its handling really comes alive. I used it for HONC 2009 and it was brilliant, handling the road and off road sections with aplomb.
Having said all of that, I wish I still had my Cross Check as a single speed 'cross bike in addition to the geared Peregrine...
Sam is, AFAIK, out of stock of Peregrines so that may sway your decision depending on when you want to buy one?