Until a few months ago I was still using a Coolscan 9000 for 35 mm and MF, and my Imacon III for 4x5.
I have just sold the Nikon. the Imacon is significantly sharper, does have more DR and no Newton ring problems, but dust can indeed be a real pain.
Carefully cleaning the slides before scanning can reduce greatly the time wasted in cloning. I will never be zero though. It is important also to scan in an environment that is as dust free as possible. A room with a carpet is no go IMHO.
Regards,
Bernard