I've not actually done a conversion on a uyllsses but have done them on peugeot citroens and renaults as well as many transits. None of these vehicles has been less smooth afterwards. I think it is important to use a proper valeo matched kit and not some mix and match flywheel clutch combination. As you said the conversion kit is vastly cheaper in most cases. A peugeot 308 hdi I did recently cost less for the 4 part kit than the cost of just the DMF. As you are no doubt aware these vehicles are virtually identical to the similar peugeot and citroen models, and they work fine on them. DMFs were invented by LUK and Valeo have reluctantly followed, but I think you can see Valeo's lack of belief by the fact that they actively promote their solid conversion kits! I personally believe that dmfs are a marketing exercise. Work it out. When every car had a solid flywheel a clutch kit cost £50-£250. Typically about £100.Now you need a DMF as well. Add on £300 to a clutch change. Turnover increases dramatically for the clutch manufacturer.