In my opinion, water drainage is about the same. Both IK's will always have some water drainage issues especially if you are paddling class III - IV water. Obviously having water in you boat will effect the performance of the boat, but that will happen with either boat. On the plus side, the Outlaw seating width is 4.5 inches wider than the Tomcat. This will provide a larger displacement of water when and if the boat takes on too much water. The overall length, width, bow/stern rocker and floor stiffness of the outlaw will provide you with the best experience. I currently instruct individuals in both IK's, the Tomcats are the last to be used!
As for the performance of the Outlaw on drops, it is far superior than the tomcat because of it's higher rocker profile in the stern/bow. The outlaw is 18 inches bow/stern while the tomcat is 13 inchs bow and stern. Also the floor of the Outlaw is 4 times stiffer than the tomcat, which means that the outlaw is far less likely to fold or pancake when you hit the drop or breaking wave.
The dog whisper has spoken