I have liners also but have not experienced rain inside yet...I find it simplier to remove liners and take in to room than to take bags off or to carry clothing exposed...lock bags onto bike and everythings good to go.My dealer has asked if I carry anything in bags as they appear new!!
One of the things I like about the panniers (and top box) on my Tiger is I can take them on and off with the turn of the key and carry them like luggage; great for packing and unpacking.
The Bags on my FJR were like that and also the ones on my Trophy, although they are a little more work to get off. Some good liners for the R3T bags would have been nice. I just pack everything in a smaller bag and stick them in. Not like I need a lot of clothes for a trip.