It's not that he made it heavier, it's that it came out heavier. The stock part is cast and hollow internally to the hub center. His is milled through. Short of live tooling on a CNC lathe, you'll spend an inordinate amount of time milling away the bulk of the material left over to gain what, 2 pounds of weight savings? It's not that critical really.
I can see that many would pass on this setup due to the expense, but given that F hubs, disks and calipers are becoming increasingly more rare, it's a nice solution. Unlike the CycleX, this is not an adapter but an entirely new hub. The unit they had on the market in years past was replacement rotor carrier installed in the drum. I haven't looked Waterhouse they changed that design or not.
But I'm rather happy with the result and it will allow fully modern brakes on my boys bike. And
never underestimate the importance of your rear brake Mick even though it accounts for less than 20% of stopping power, it is critical in many circumstances for safety, control, or emergency stops.
Anecdote now: I rode for probably a good 10 years almost never touching my rear brake. Then I hooked up with a VA State Trooper who rode on their bike unit. I was taking my then girlfriend to her MSF Class. The Trooper and I became friends pretty quickly as both were riding BMWs. Anyway, we were off riding in the Blue a Ridge (70CB will know these roads) and he was flat out eating my lunch up and down the hills. We pulled off for some lunch and I asked, "Okay, what's up with the dust trails?" He laughed and said, "You need to learn to use your rear brake to ride better, more safely,
and faster."
So he gave me some pretty sound instruction, section by section and many pointers. The next class session, I hopped on my bike and did nothing but brake drills, all rear brake. I will tell you, in my opinion, it is quite possibly the single most contributing reason why I've never been on the pavement from riding. Good brake skills (front and rear) matter.
Devin's hub isn't anything special above an F setup, other than perhaps a made-for modern rotor, but I know I could retrofit a modern rotor to an F disc. I am just delighted to have helped span a new, missing product for these vintage bikes.
Anecdote over.