How many degrees does it take off the close hauled course, exactly? I mean, I don't understand the physical principles that would make a free standing mast unable to beat upwind as well as shrouded masts.
Is it just the fact that the mast bends and you lose power?
The simple answer to your question is that the Vision will give up a few degrees of windward tracking ability but, unless you intend to race, that is not much of an issue unless you are worried about becoming embayed on a lee shore in a gale, eh?
Free standing masts are not new technology. They have been around for thousands of years. Free standers are also very common on small sailing boats, think Opti's, Pelican's, Flying Fish, Lasers and the like. Gary Hoyt founded Freedom Yacht's in the mid-1970's to build a line of yachts that could exploit the simplicity of the rigs to good advantage. They were/are very good boats but were/are viewed with suspicion by those raised and schooled on traditional fully supported rigs. A disadvantage of the free standing ring is that, as the weight of a boat increases its resistance to heeling also increases and, the amount of sail area necessary to move the boat at any reasonable speed also increases. When confronted with the loads imposed on the spar by much increased sail area, an unsupported spar will fall off or bend to leeward, shedding wind load-hence power-and so, efficiency. To counter this--to some extent--one can increase the stiffness of the spar but the resulting weight gain, unless the spar is tapered, is counter productive. Of course, tapering is costly. They laid-up carbon fiber spars of the Freedom line were very costly as they were not produced in great enough quantities to exploit economies of scale and they were also viewed with suspicion and distrust, particularly after the disastrous performance of the carbon fiber rudder shafts in the Fastnet in '79.
Warren Luhrs--Hunter Marine--developed the Vision series of boats for comfortable, easy, uncomplicated sailing and, while not my cuppa tea, seem to be very good at serving that end.