hogdog's shells ejecting into face would be a complete no-go on a gun for me, any gun. He said "under" but if the shells are passing under then a slight tilt and they would be into the face. Beyond that, there is no reason bullpups would not be practical for HD. In fact, they may be much more practice for HD than other shotguns simply because of their reduced length which makes them more viable for use around corners and tight places.
There are advantages and disadvantages regardless of gun length, but for interiors, I prefer shorter guns.
I have a short Rem 870 with an 18" barrel and Knoxx Spec Ops stock without its recoil pad that is a bit shorter than a youth model 870. It still comes in at a whopping 36". The KSG is some 10" shorter which is impressive. The High Standard and UTS are comparable.
"If you look through your scope and see your shoe, aim higher."
-- said to me by my 11 year old daughter before going out for hogs 8/13/2011