I race a lot on portsmouth and only recently have had the experience of REAL class racing with the Stan "the motorboat man", Rick, Sharron and a bunch of other Hobie Waves at I-LYA.
Kenn, the only time picking a lane is important in a divided open fleet is right at the start - then everyone fans out and it's a matter of making your boat fast. Should I cover that Supercat 20 Tall Rig with my Nacra 6.0NA? NO! I owe him 3 minutes! What would covering him do for me besides ensure that he finishes right next to me and beats me after the correction?
Try one design. You'll never feel better about a great start that gained you 2 boat lengths when you win first place by a nose and covered and fought tooth and nail the whole way around to guard your position. I'm a speed freak with my 6.0NA+chute and while it's not going to get sold any time soon, that little slow poke Hobie Wave gave me the greatest thrill and the best learning experience I have had to date.