Not true to a significant degree - Similar boats 320, 34, 36. Yes, the 36 is faster. Some folks feel the 320 will sail a bit faster upwind than a 34, but I get spit out the back boat for boat with a 34. It's more equipment, sail condition, and skill related than boat design. For a cruiser, he won't see a significant difference. If he races a lot, the 34 group has more owners available to share information and fix any GAPs in his performance. There are more 34s, they have been in production longer, and there are older and less expensive boats available. The money he saves on purchase can buy him a folding prop, new sails, and a smooth bottom, which all will make the 34 sail to it's potential. The 34 has a larger v-berth, the 320 has a better galley and head, and the 36 is just a bigger boat. The 34 has a bit more sheer and a stiffer/heavier rig than the 320. All of the fin keel boats outsail the shoal draft versions. YMMV