I don't see any reasons that it shouldn't operate at all comparable apparent wind angles as any std rig.

I do believe that the leading edges of my headsails likely need be 'detuned' such that they don't produce too sharp of an incidence angle for the wind, and thus become to easy to stall the airfoil of the sail. Several experimenters have noted this problem including Bolgers aft mast rig. This actually could become a critical point to consider in designing/deploying this rig, and having the everyday sailor enjoy it. I've suggested a purely round (bulky) furling foil, which incidently furls the easist.

Aero drag is the other limiting factor to its upwind performance. But do I really have any more total drag than a two masted cruising boat ??...I have no second mast, nor assoiated rigging.

If I utililize an existing mast tube with its existing mainsail slot, couldn't I fly a piece of material (maybe even thin plastic) in it, that would greatly improve its aero drag characteristic, just as with a sail in this slot??

Or how about if I had no mainsail slot but rather a custom mast tube, could I attach two thin membrans of rigid plastic material (or other) to either side of the mast such that they extended into the wake of the mast and then slid against one another at their tips to produce a nice teardrop foil shape overall. I've got a sketch of that around here some where...will have to find it and scan it.

Meanwhile here is a top view with 3 different wind angles

So yes same AWA as normal rigs.