Stuart,
The Tubus clamps work great. I use them on an 80's vintage road bike and have for a long time.
Both of your mountain bikes are titanium, correct ? Cool that you live near your builders and they are able to add braze-ons to make amazing frames even more versatile. I am in Austin, Tx and find that I don't need suspension on the bikes I use for commuting. For me, old steel rigid mountain bikes from the 90's meet my needs on most trails and make an easy transition to gravel roads, hardpack, and pavement. When riding our trails with big hills, drops, and big rock recreationally, I prefer a more modern suspended mtn bike design with at least shock up front and big floaty tires. I would think the bikes you have would be near perfect if living in Colorado.