Be careful to not get lost in the marketing hype. You can get some real world data looking at the ARC Rally results from past years. The difference between performance and charter boats is usually less than a knot VMG or 20-30 miles a day. That delta is meaningless when hopping between Carribean islands. You should also consider on a charter boat you may not have the sails onboard to reach the sailing design specs and too much water and people stuff holding you back as well.