I have owned and paddled the closed foam floor lynx. Disregard the people that tell you it will take on water...it doesn't. It is closed cell foam. The only significant downside is that the boat won't roll up. That is all... As mentioned above, it is in 3 pieces so it can be folded but it is really just easier to treat it like a hard shell and strap it to the roof.
Some people love the foam floor. I feel like it is a very small difference overall. The floor is a bit lower on the foam floor boats, making them seem a bit more stable to me. $350 is a good deal if the zippers all work well, the valves are solid, and any patches are well applied.
You can tell the age of the boat by looking at the last two numbers of the serial number.
Also, take a look at the condition of the cargo loops, they can be damaged over time and are not easy to replace.
Last side note...if it has the ~1996 really weird wedge chair, replace this immediately. They are terrible...Sotar IK seats are on sale until April 12 for like $46 or something.
but can you see its opposition | comes a-rising up sometimes | that it's dreadful and position | comes blacking in my mind | ....and then I see a darkness