The Uni-Fi is a true 3-way bookshelf with a concentric high/midrange. It definitely sounds better than the Debut 2.0's in terms of soundstage, imaging, etc. Bass is way better (with a stout amp), but since you're crossing over to sub that might not matter.
How many Uni-Fi's will you be driving with the AVR though?
For the record, I own both the Uni-Fi tower and bookshelf. While both sound much the same, the tower more effortlessly fills/pressurizes a room with sound and has a much larger presence.