Kelvin, the ribs look really good. It does seem like a long time for baby backs, though! You might check your box temp to see if it was really smoking at 235. I usually smoke 3 racks at a time, and never even reach 6 hours before they are done perfectly.
You brought up a good point about smoking whole racks... One end of the rack is always much thicker than the other. I always cut my racks in half, and probably would, even if I had a #3. The reason? Different cook times. I put the thick ends on the lower rack, and the thin ends up top. That way, the thick ends cook faster (closer to the smoke box) and finish the same as the thinner ends. If you have a rack that is uniform thickness all the way, go for the full rack cook.