pdukey, I very often use a 120 foot hank of New England KM-III (Static Kernmantle) to establish an adjustable false crotch at my tie in point, running ArborMaster Blue Streak through a 2-3/8" pulley on the end of the kernmantle for a "Friction Saver", and then climbing the Blue Streak in a dynamic system. I get the benefit of the Kernmantle abrasion resistance at the crotch, I don't have to worry about isolating limbs with my Blue Streak, I get the mechanical advantage of the doubled line dynamic climbing system and the friction saver, and I get practicaly no wear on the Blue Streak except for my friction hitch. Any wear on the Kernmantle is limited to the end where the pulley is tied. The Adjustable False Crotch also saves wear on the tree cambium, especially important in recreational climbing (as someone pointed out in another thread).
The Kernmantle I have is too stiff to use by itself in a dynamic system, as it sounds like you are useing from your reference to the Blake hitch. As the name suggests, it is designed for Single Rope Technique (SRT) or double rope static technique (DbRT) rather than Dynamic Rope Technique (DRT or DdRT).