Off topic but related: I raced the Grand Comp sidepulls on my '76 Fuji Pro. Very good brakes: I did have to keep in mind I had more stopping power that just about every other bike in a race. (This being when Campy NR was universal and adhered closely to the Enesto Campagnolo philosophy that no one won a race by stopping; that brakes were mere,y for speed adjust.) When it came to working on the brakes I liked the second cable release at the lever, that piece of the top of the lever that swung away and allowed the lever to open further. Yes, it seemed a little corny on a pure racing bike but ... in a race that meant a lot to me, I was taken down 5 miles from the finish. Just bruises and road rash, bike fine except a wobble in the front wheel so it was hitting the brake pads. In my chase, I really did not want to reach down for the release lever on the caliper, but thanks to Dia Comp I didn't have to. Just flipped off the release on the lever. Second plus - I still had full braking power with no changes except having to reach a little further for the lever. (Not that it mattered; I never touched the brakes the rest of the race.)
Only gripe with those brakes - the levers were too small for my hands. But I didn't get my eyes opened to that fact until I put the far bigger Mafac 2000 levers on my username bike a year later.
And my other related the topic: Running those Grand Comp centerpulls (or the equivalent Weinmanns) as a rear brake and running the housing the full length makes them a great match, feel and performance-wise to a Mafac Racer front caliper. I have Schwinn approved (presumably Weinmann) rears and Mafac Racer fronts on my two winter/rain/city bikes. Those bikes stop really well. Lots of power but very predictable and with great control. A car cuts in front of you and hits the brakes. With a pure adrenaline squeeze, you will stop really fast. (It has never crossed my mind that they needed "boosters". Perhaps I just don't weigh enough.) I like that both the Weinmann (and I presume the Grand Comp) and the Racers can be turned into the other application, front or rear, by just going to a hardware store and buying the appropriate bolt. My two mixed pairs were simple two matched sets from different bikes. (And my favorite joke, no longer true; you could always get a near NOS set of Mafac Racers for $50 - but you had to remove and dispose of the attached Peugeot UO-8. In the '80s, there were hundreds, thousands, of UO-8s bought in one of the bike frenzies and never ridden.
Ben