Yes, there will be a big difference between your current 12’ rec kayak and a transitional touring kayak around 14’. And there will be a big difference between a transitional touring kayak and a 16’ touring kayak. And there will be a big difference between a 16’ kayak and the 18’ fast touring kayak listed above.
“I’m 28?, around 5’8” 185 lbs." and it seems like you desire a kayak with nice efficient glide. The Epic 18 Endurance will give you that to the point where you will enjoy gliding across a wide lake. What you have is closer to paddling an innertube across a lake than it is a fast sea kayak. It might be a great choice for you. It might not. That Stratos 14.5 will feel like a slug if you become a skilled paddler in the Epic. But it will feel fast compared to what you have. It will maneuver exceptionally easily compared to the Epic, be more stable, and have significantly less efficient glide. Consider Bill and Bob. Bill is going to paddle a quick 2 miles across the lake, and not be bothered a bit that he’s taking a wide gradual turn to go back, or that he has to really commit and use some effort to make a quick turn. He will enjoy learning to maneuver his fast kayak around the bends in the river, and becoming good at it. Bob is going to completely forget how nice that glide was going across the lake when he realizes it takes more skill and effort than he would prefer to get it to turn. His frustration comes on quickly and overwhelmingly enough that it won’t matter how much quicker he was or less energy he used during the straightaway sections. He doesn’t want to trade off very much ease in maneuverability in exchange for more efficient glide.
Then there’s the care piece. Most are pretty careful about handling something like the Epic off the water, and careful about what they run into or over the top of on the water. A poly boat like the Stratos typically evokes less concern.
You should try something like the Stratos. But you’re young, and like speed. With a little skill, you can maneuver a Current Designs Sirocco nearly as quickly, and have much better glide than the Stratos. So you should try that too. And you should try something like the Epic 18. Then there are surf ski sit on top designs that span the range of stability and efficiency. And there are boats that fit in everywhere in between. But if you could try 3 boats like that, and one of them really spoke to you, you would have a much better idea of a range of different boats that you’re interested in. I know the Dagger Stratos and Current Designs Sirocco are very good choices within their respective categories. And I think the Epic 18’s are well-respected in that category as well.