we carried our hard shell kayaks on our truck for 7 years. last year we sold truck and got a jeep grand cherokee which was too short to carry the kayaks. we sold them and bought 2 inflatables. they are terrific. they are strong (i feel safe-even just kayaked in the louisian bayous where alligators were known to be present), and they track very well. i truly see no negatives compared to our perception kayaks.
i would highly recommend inflatables for a)ease of blowing up b)tracking c) convenient to carry and store
the only down side we found is drying them off so they can be stored. you probably need to keep them out for a few hours before putting back in their bags.
the brand we bought was advanced elements from an online company called air kayak-they were extremely helpful and had the best price. if you do purchase them, i would recommend the upgraded floor-much more stability and more comfortable!
ps...we're headed to crysal river florida tomorrow---anybody have any good kayaking or road biking information? thanks!