Run a search on the CGOAB site, there are quite a few people that have toured on Titanium frames, some stock and some custom. Titanium itself is a reliable metal, the question probably should be about the frame maker rather than the material, and how they build the bike.

FWIW I had one of the early Teledyne Titan framesets and mine failed. At the time I was a lightweight rider ~135#. The bike was interesting to ride. I was light enough that the only way I could flex the frame was to sprint out of the saddle. Bigger guys got flex under regular riding conditions.

Aaron