The Porta Bote is a fun boat and does allow you to do somethings that you can't with a regular hulled boat. Areas to look at closely, is the folding points on the transom area, other than those sometimes cracking I have never heard of any of the other fold points cracking or leaking. Porta Bote company, is not the most helpful company when it comes to gathering information and you will rarely get an email answer back from them, you have to call them on the phone.
I have a 14 footer and it is heavy, not easy to get up on the top of the truck. I tow a 5th wheel and am going to make a set of brackets like they sell for way to much money so I can carry it on the side of the trailer. They seem to be very durable, I ran a 3 horse on the back of mine last summer, it was slow, but got you where you wanted to go. I sure it could handled a 5-7 hp motor with no problems at all. You can normally tell the age range by looking at the style of the boat and the type of hardware, mine is a genesis iii model, I believe they are on genesis iv now and then the original model had the pinched butt transom on it.
If I were to do it again, I would get a 12 footer over the 14, quite a bit of difference in weight. You can normally call them with the serial number and they will tell you what year it is, the one I purchased had never been titled or registered before, so I had very little paper work on it, so they issued a new statement of origin for mine so I could title and lic it.
Also, one thing, track down extra seat clips, they are a proprietary clip and they are expensive if you buy from the company, also be aware, often times you will find them with homemade seats in them, because the PVC they use to make the seats gets brittle over time and exposure to UV rays from the sun and they will break up after a few years, make sure you get the stick that it used to open the boat for set up or you could end inside it folded up, look at a few videos to see the proper procedure for setting the boat up!
They are fun, they do what they claim they do, but as with all things, they do have their own set of quirks to get used to!