I should have picked a better word than "traditional", which isn't quite right as you say. Perhaps "unproven", "run-of-the-mill", or "inexperienced". It may entirely within the skills of a good "traditional" contractor to do right, but there is at least a bigger downside with potential mistakes due cost of repair, if not a substantially greater chance of mistakes due to the abnormality of the building. So, it's important to be picky.