If you are within driving distance, go check it out. The Solstice is a nice kayak but you are going to need to minimally sit in any boat you plan to buy to see if it fits. Obviously, paddling the boat would be better still. The gel coat repair should be of no consequence.
The Solstice is a terrific kayak and its design and size would seem perfect for you. Once you pick up some paddling skills that boat will take you anywhere you could ever want to go. And I agree that a gel coat repair isn’t an issue.
As @pblanc says though, you should go try it out - or at least sit in it - if you possibly can.
I can’t help but agree about the solstice. It’s always been a good design and is smooth and fun in the water. If the boat is in good shape, and within budget, it would be a great first boat for someone your size.
The only concerns are, really, it’s condition and if it “fits” your paddling personality. You’ve already experienced what wide stable (slow) boats are like and didn’t like that, which suggests that solstice will fit your personality better. It may feel tippy at first, but you will quickly learn to keep your body (knees, bottom) in contact with the boat and how to use your center of gravity to keep the boat in balance.
Still, there is a bit to learn about boat handling and finding a club, class, knowledgeable paddling partner, etc. can do a lot to speed up the learning process.
I’m guessing that you are located somewhere in the Portland area, or at least within driving distance. If that is so, there are a ton of used boats, so I wouldn’t jump at the first one. If you are able to, you should go take a look at what Alder Creek has for used boats and the same for Portland Kayak Company and Next Adventure.
You are a pretty big guy, so you are going to be quit snug in a lot of boats–depending on where you carry your weight. There are some very nice boats that are made to fit large people, but finding one used might be a challenge. I wouldn’t rule out a sit on top if you find cockpits too tight.
You are looking at a used boat in Portland area, so presumably you are decently close to there? The shops in Portland (Alder Creek, Portland Kayak, Next Adventures, etc) do rent/demo touring kayaks.
Better yet, I would suggest you sign up for a day long intro to sea kayak class from any of these shops before you buy a kayak. There is a lot about kayaking that is not intuitive which the class will cover. Plus they should cover what to loo for in a kayak and how to buy one (if they don’t have that as content, use the time to ask questions). And consider it also demo time in a kayak, as they will find a kayak or two that fit you and you get to try them out as part of the class. Well worth the $100 or so it costs for the class.
I agree that the Solstice is a great hull, big enough for you and would probably suit you well - I say go for it, as it is not that much money. Buy a really good light paddle if the one it comes with is heavy. A great paddle will last for years and make you happy.
I’m going to disagree a little with the caution statements above - you could feasibly buy the Solstice and paddle it into the fall and really find out whether you like it. If you like it, then you got a great deal. If you don’t, you could probably sell it for what you paid while learning a lot about what you want, meanwhile enjoying a long-term free rental. This will tell you far more than a one-day demo — finding out what you want takes a lot of hours in many types of weather and paddling conditions. Going through a series of used boats is a lot of fun, in my opinion. Taking an intro class is definitely worth it, and you could do it in the Solstice or a loaner.