I love the unit and the open view. The only reason I gave 4 instead of 5 stars is this unit is said to be used on brick or masonry or wood or metal. Every one I know has vinyl siding.  I installed it any way but if the r & d department can come up with a solution to that issue it would be even better. I don't know what will happen to siding  down the road. 
 Cost a little more but we'll worth the advantages of the over sill design.