You're asking for two conflicting things; carrying capacity and maneuverability. Carrying capacity is related to tube diameter and the length of the boat. Maneuverability is related to rocker and length of the boat. The longer the boat the less maneuverable it will be and the greater carrying capacity, and vice versa for a shorter boat. I guess you don't care if the boat is PVC or Hypalon (Pennel Orca), since the two boats you are looking at are made from one or the other. If you're going to stick with a tandem IK then you're automatically losing that maneuverability. Most of my IK trips have been in tandem boats but I'm a big guy at 6'2" and 240 lbs. so I wanted big tubes and a tandem boat. I run Class II-III all the time with the tandem boats without problem. I recently bought a solo Padillac and that seems quite sporty compared to my tandem Padillac or the tandem Tomcat I had before. The Padillac has the biggest tubes out there at 13", the Outfitter II has 12.5", the Maverik only 11", that's a big difference in capacity. Another PVC boat you may want to look at is the Zoik RF II. I have four friends who've bought 6 of the solo Zoik's and they seem to like them. I've paddles the solo and found it quite maneuverable. The Zoik's have 12" tubes and are PVC boats. Zoik RF Tandem Inflatable Kayak
The other topic you wanted addressed was Aire/Tomcat bladder boats compared to everyone else. I started with a Tomcat and used it for 4 years. It held up really well for 30 day-trips and a couple of San Juan and Green trips. When I sold it, it was still in great shape. I got rid of it because it's a pain in the A## to clean and dry. If you don't care about boat cleanliness then this isn't an issue. If you do you need to unzip the outer shell, soap, move the bladder, soap, move the bladder, soap, move the bladder, rinse, move the bladder, rinse, move the bladder rinse, etc... then dry, move the bladder, dry, move the bladder, dry, etc... And that's just one tube, you have another tube and the floor to do. Now, put the bladders back in position, zip-up and start the process again next weekend. For every other manufacture, just soap, rinse, air dry, and roll-up.