This is just “my opinion” so hopefully I don’t get jumped on by the 518 owners. lol I personally don’t like the way a 518 rides. A couple of years ago I fished out of one at Shelbyville and I honest to god thought I broke my ribs. It was the roughest ride I have ever had in “little” water. Now 520’s are a whole different story. Those boats are very nice.
If I recall correctly (which I might not be) I think the 518’s are actually 19′ but 1′ of that is the transom setback that acts like a jackplate.
My choice between an older 520 and a newer 518 would be easy. 520 without a doubt. Of course my overall choice would be the Triton TR21X but that wasn’t part of the question. lol
JT Bagwell