As to whether the sailing characteristics are much different, I wouldn't think so, but I don't really know. As for building, they require the same attention. Maybe the 15 requires a little less sanding, but not significantly less. My decision about size was based on storage space and launching as even a 15 would be big enough for my use. I knew I was moving to Florida for retirement, and garages in Florida are often 20' deep. My Lapwing on a trailer is 19' 8" long. The CS 15 on a trailer would be a tad shorter, and a 17 on a trailer is probably over 20'. Based on all of the build threads I have read over the years I think I can say that anyone with some patience, a little skill and willing to ask questions who find the idea of building a boat fun can succeed. I like to stress the fun part. If you are building just to try and save money you will find building a boat tedious and used sailboats in good condition are often cheap. I think the 2 best reasons to build a boat are: it is fun, and you can customize the details to your specs. I never recommend changing design details as you will likely sacrifice sailing characteristics as Graham and Alan have done a great job already. Even with the Mach 3s, which were designed to add siginificant comfort to a pocket cruiser, the boat had to sail well first, or they wouldn't desing it.