In Spain I have a king size synthetic comforter that I can just about cram into my Miele W1 washer. After the 1600 RPM spin, it fits easily in my Miele T1 heat pump dryer (although it fills the drum) and it dries completely no problem (although ends up very creased). However I do always use it as a duvet by putting it inside a duvet cover (which I iron), so it doesn't get washed often. We also have a double down duvet in the guest room and that gets the same treatment.
I'm currently in Goodyear, AZ with a Maytag Neptune washer and gas dryer. The washer copes fine with comforters and bedding. The dryer can dry comforters just fine, but they always end up creased and so I try to iron it once on the bed. The dryer does tend to ball other bedding, just like my Miele in Spain. I have also washed a comforter in an older Maytag belt drive TL. Works ok, but I think a FL is better for comforters.
I am very envious of Gary with his 1980s British Hoover vented dryer that reverses every 37 seconds. I would love one of those. Although the Maytag gas dryer, with its 6400-Watt burner and fast airflow, does dry very quickly but it can leave duvet covers and fitted sheets in a tangled mess!
Mark
P.S. I prefer to have a fitted sheet on top of the mattress protector and then a duvet or comforter inside a duvet cover. I just can't get along with bedspreads and top sheets between me and the comforter -- hotels often do it that way and the whole bed ends up looking like a war broke out after I've tried to sleep in it. How about you guys?
[this post was last edited: 9/4/2015-00:40]