On account of the fact that you a) have a personal coach and the coach is recommending that you further your sailing career in a vago, I assume that you are American.
Whilst I wholeheartedly endorse my friend jwlbrace's recommendation that you chose a 29er, I feel compelled to clarify that, on completion of a hearty day's sailing, that he sagely commends you to find some beer and attempt to "hook up" with a comely fellow sailor of the opposite gender, or same gender depending on how your bread is buttered.
Whilst, if we are honest it is how most of the evenings of our nascent sailing careers ended, I was mildly concerned that you may have interpreted jwlbrace's backwater colloquial English vernacular as an instruction to find beer and, shall we say "rough up the suspect."
(divided by a common language)
Summer in the UK is sometimes a week long, sometimes less! I was a member at Hayling Island and sailed Fireballs and Ospreys there and sailed my Laser at Stokes Bay, Wednesday evening races had, amongst others, Steve Cockerill, Ben Ainslie and Hugh Styles sailing, those were the days!
A couple videos of the D Zero prototype sailing in the Czech republic and Valencia, Spain.
The D Zero reflects 5 years of development on the the "Punk" prototype created to fulfill the brief of "The performance beachboat for the 21st century"
Recreational versatility and robustness matched to sparkling performance, style and ergonomics.
Built by the passionate and skilled boat builders responsible for every medal winning Finn since 1996 as well as the spectacular D One and Melges 24
Sail by North Sails One Design - masters of the modern unstayed rig and winners of every Olympic Finn gold medal (and quite a few others) since 2000
Spars by Compotech (as D One)
Full harken fitout
4.2m x 1.42m x 0.38m
8.1m2 semi soft laminate sail on halyard - rake adjustable by chocks - competitive sailor weight between 70 and 90 kgs
Hull weight 40kgs. Light by any standard, but robust. I wouldn't recommend anyone lift it (or anything else above 25kg for that matter) unless in a gym for which they have been inducted by a fitness professional.
Tasty introductory deal soon to close.
Global distribution / dealership network, get in touch to arrange a demo sail.
I imagine that the soft MTB tyres are about maximising contact patch and grip etc.
I know that were I to swallow my pride and don lycra and get on a roadbike and cycle up a hill on a straight line on tarmac, that I would want the stiffest frame / tyres I could (assuming equal weight...)
This is because work done (energy) = force x distance moved in the direction of the force. If I am doing work to deflect a less stiff frame, that is all propulsive energy that is not being used to go fwds.
So back in the boat, simplistically speaking any deflection of any part of the structure due to dynamic loads will be taking away kinetic energy from the boat, that, were it rigid, would be used to propel it.
In a jib headed boat, then stiffness (global, i.e how little headstay deflection you can have for a given dynamic acceleration) has a big effect on how quick a boat goes in waves. Almost any boat can be wound up to a certain rig tension at the dock, but the stiffer one will have less headstay sag in the dynamic environment when the boat hits waves etc, or even when sailing aero loads are applied. Headstay sag is doing the opposite of what you want when the boat loads up (more depth, less twist etc) so is slow.
The unstayed boats are a little different because you can decouple the dynamic response from the rig to an extent - means you can have a stiffer rig or less sailor input (steering/kinetics) in the dynamic environent, so the boat will be in balance more often or demanding less of the sailor.
Talk of harmonics is a little bit much - the natural freq of what is essentially a box in torsion for an unstayed boat will never be close to that of a long cantilever. Unless the hull is built of cheese or something.