As I said there are issues with the sunroof caused by lack of maintenance and trying to open them with ice on the roof. I just bought an X3 3.0 with just one sunroof issue. I got a good price I dont regret buying it. There is more to a vehicle than it's sunroof. I drove the stripped down 2.5 litre 3x and found it to be not nearly as fun to drive becasue there is significantly less power. Even if you by one with a nonfuncional sunroof for a good price it's the same as having no sunroof. I paid $10,700 for mine which was about 3k less than others currently available in my market.
One problem is people dont maintain these sunroofs they need to be frequently cleaned and relubed. They are full of plastic parts that are sensitive to sun degredation when the roof is open and to a ceratin degree when closed. Plus there is a lot of dirt and dust that accumulates in the tracks; like I said the other day just look how dirty your hair get when you ride in a convertible for an hour imagine what how that effects all those light watch mechanism type parts. The road dust gets inot the tracks mixes with the old dried out lubricant and exponently increases the drag on the pullies and cables thus stressing and ultimately breaking the fragile components. With most smaller sunrooofs this isnt a problem but with the panorama roof the area is much larger and as result many more parts are exposed. Plus because of the multifunctions and hundreds of parts involved there is more potential for probelms; End of story- if you got one-keep it cleaned and oiled.
Dont use anything but BMW sunroof lube about ten bucks a tube. I am not a big proponent of proprietary lubes- I have never used BMW oil or tranny fluid but for some reason after I lubed the sunroof with off the shelf lithium grease and spray silicone lube it actaully sounded worse? So I cleaned off all the off lube with cotton and a little alcohol and relubed it with the BMW lube and it was whisper quite. The BMW is a little bit like KY jelly. I dont think it's worth harming a $4000.00 part to save $5.00