JPBARNA - you asked re stance. Think about the distance from the the mast track to feet on the old freerides vs the new. Its a massive difference. Then tail width (which equates to fin size) - in early 90's we used 26-30cm fins, now 36-40 in same winds. It is just different in every single way. It will be very hard to get good at planing windsurfing if you bounce between very old fast boards, and new style fast boards......... like learning to drive a manual car but every single lesson is a different clutch engagement point. You'd hate it.
Have a read here (and anything Basher says about old vs new stance, he explains it well, so look for threads on this site about stance)
www.seabreeze.com.au/forums/Windsurfing/General/Modern-Stance-for-Maneuverbility-?page=1I still say have a long board (with centreboard) for when its light and then as soon as it might be planing windsurfing (14kn plus for you) get on the Rocket and stick with it. Probably the best freeride board ever made. Yes there are old faves that are fast, or better in chop but the stance is different and they don't gybe well, there is a reason they went away.
67kg on a 105L Rocket with a 6.5 no cam freeride? I wish I could do that in 15kn, you would be fully lit smooth water and so much control. Best way to learn everything and have bulk fun.