Very nice work!
Well, after (more) delaying, the job's done - the JB Weld is absolutely solid. So far I've taken it on one proper 24 mile ride and commuted on it for 2 weeks (only 6.5 miles each way but a pretty good shakedown test) and I'm extremely satisfied.
Ride quality is excellent, extremely smooth but also responsive due to the springiness of bamboo. But it's hard to isolate the effect of the 35mm Schwalbe Kojaks which are very quick-rolling and supple, with a weight comparable to 23mm Gatorskins (though very little puncture resistance). Flex in the front triangle is noticable under heavy effort but has no negative effects, though combined with the very low trail design it did feel jittery at first. The rear triangle is as stiff as I had hoped.
A very short stem (Cinelli Ant, 60mm opposed to the 90mm Planet-X Superlight one I had before) gave me a better position on the bullhorns - I was previously a little stretched out as I had sized the frame and stem for drop bars - and also actually reduced shimmy by changing the balance of the front end very slightly, an interesting result that I hadn't expected.
Braking performance with the TRP Spyre disc (post-recall revised version) is obscenely good. I know disc brakes on road bikes are a fad etc etc but I wouldn't willingly go back on a new bike now; braking performance is so much better for only a reasonable weight penalty. It pales into insignificance when you take into account my old man Carradice saddlebag and half-kilo steel Bagman support ;)