Yeah, understand where you're coming from but if it's simply a failed weld and nothing more insidious then replacing the weld should be ok? (Subject to specialist advice!)
Yep, It's a disc mount all right, placed lovingly on (looks like it's always been there!) by Paul Donahue (Donahue Cycles), bad news tho' boys, he's packed up and gone back to sign writing!
The Bonty also has been drilled out for rack mounts! The guy used to carry a child seat on it!
If it was done by Paul Donahue, it may have been done by the talented Kevin Winter, who used to work for Paul. The man is a genius, he does a lot of frames under a different name(contracted so can't say who) Doesn't have a website or anything as he has so much work from word of mouth. He repainted my Stumpjumper and made my mate a Columbus Foco MTB frame
I did...that's why its still hanging on the wall (for now) (I got the impression a repair is quite a different propositon to a additional modification such a disc mount). All the same awesome bike :!: