i read your post and then read it again but am a little unclear on your expectations of 13ft-14ft raft... are you expecting to haul 5-6 people on overnighters?
anyway, in the course of the several years of owning rafts I have migrated from cluelessly buying a 11ft raft first...way to small. a joke really. got rid of it ASAP. Bought a 13fter next...nice size for rowing 1-2 passengers on light extended rafting trips or 3-4 for day trips. 14ft more room but about the same as a 13ft then moved to 16ft for extended trips w/ cooler, 2-3 passengers. I can't imagine anything less than 16ft when you have several passengers anymore. it gives the rower plenty of room to work the oars w/ out worrying about taking out passengers if the oars catch too. passengers can have elbow room too and room for one to fish up at the bow too(w/o the other passenger having an ass right in their face). 16ft is a big boat but it's surprising just what you can run in them at low water just as well as a 13fter. the bigger tubes keep you higher in the water, ya know?
also, keep in mind, the overnighters are addictive and quickly lead to week long trips and not enough room for everyone that would like to go. i bought my first raft for fly fishing from, only in super mellow water, on the cheap and day trips... then i found how fun it ALL is...
btw, my hyside is 14 years old and i added air once on my last 7 day river trip. it's still in great shape. if you take care of them they last a very long time. 303'em. http://www.mountainbuzz.com/album_page.php?pic_id=817
i had a aire for a spell too. did not like the PVC and really didn't think the floor held up well to abuse from rocks. just my opinion.
anyway, good luck.