I’ve an ali framed disc braked touring bike in the shed on which everything bar the front mech would fit the Kaffenback Disc frame and fork.

Worth the ‘upgrade’ or no?

I like mine.

But I didn’t have another similar bike hanging around that would handle laden commuting duties.

Seeing as the Kaff is a cheap frame, perfectly good and enjoyable, but not a posh sophisticated replacement, I’d say probs not worth bothering if your current tourer still works and is the right size.

Unless you just want a change. Kaff also has swapouts so is versatile if you fancy SS or Alfine etc.

Unless you just want a change

This mainly. I like the retro look and am in need of a fettling project for these winter nights!

I like mine too. Changed from a Roadrat, largely because the rear mech hanger arrangement on the Rat got tiresome after one too many punctures! It’s definitely a bit sturdier than the RR – I didn’t particularly think the RR was flexy until I rode the Kaff for the first time, but there is definitely less back end wiggle on the Kaff (when loaded). All up weight is about the same though I reckon.

Don’t know if anyone else has the same issue, but I think heel clearance is pretty tight on the Kaff, it does seem to be pretty wide at the backend. If you have big feet it might be something to look out for. Toe clearance is better, I only occasionally catch my toes on the mudguard. Neither of these things were an issue on the RR.

Run mine 1×9, 32T with a 11-32MTB cassette on the back.

I quite like mine, although nothing to really compare it to. With a steel rack and guards and sensibly tough spec for every day duties it’s easily the heaviest bike I own. I do find toe overlap an issue with guards on, but then the frame is a small so this might be better on larger sizes. Overall happy with it, but (likely due to the heavy build) it doesn’t exactly excite me as a bike. Ultra practical, though.