Hi Hoptoad
To make a  resisitive load (not shorted-out coil) resemble or mimic the heavy-handed "usually-lugging" effects of a shorted coil, you would need a resistive load of around 1 or 2 ohms - so a very heavy resistive load....
There have been a few people who have substituted a heavy resistive load like that in their Thane or Romero replications, for the "the shorted coil" effect, and it gives the same speed-up effect as a short, so this again is ALL GOOD...
yes a shorted coil is not making any power at all, but a 1ohm load means alot of power is being made (lots of amps not so much voltage)
And one thing that resembles/mimics a load of around 1 or 2 ohms is a very big UF value capacitor.....so you know where I am going with this eh!
Disconnect that capacitor from the "source" when it hits a load too (two-stage or diode plug type output circuit) ....so the only thing that causes worry (and/or lugging) when load is applied to a discharging capacitor, is the next stage, (or the previous stage) of the "filling-up" of the capacitor...
and if the rotor speeds up when a very big capacitor is filled, then once again, its ALL GOOD...
have the load be a motor, or motor coils, that is spinning the generator rotor..
have two motors run by cap-discharge, and two generators that "speed up" while filling up caps.... fill one with the other...

In both cases however the end result is still the same. No power out. The useful purpose of a generator is to deliver electricity into a useful load. If the addition of a generator onto the drive load of a motor, which, when shorted out, actually increased the torque of the motor to greater than that without the addition of the generator, then it would a great and wonderful thing. It would be considered a useful purpose, if the point was to drive the motor with a greater torque availability than it had without the generator. But the addition of the generator (conventional) onto the drive motor immediately causes more power in the drive motor to be consumed, as it makes it's mechanical inertial demands upon the torque available, with or without an electrical load on the generator output.

The additon of generator coils (with cores - air cores do not exhibit drag) in the alternative generator design (muller, adams, bedini) puts demands on the drive rotor torque by way of drag, until such time as the electrical load is high enough to negate the drag. But the shift in current/voltage phase, when loads are very high or even short circuited, means that the power factor decreases with the increasing load. So while you may get the benefit of reduced drag at higher load, the effective power out is diminishing.

The power factor in a shorted coil is effectively zero, as there is no power out. That doesn't mean that power isn't being dissipated within the coil, it simply means that for useful external purposes, there is no power out to be used. Power factor is considered when measuring (AC) power available/dissipated to a load. But in the presence of short circuit, an external load sees nothing.

The rotor speed up in some generator configurations is merely the negation of the core/s drag. This drag would not exist if they simply were not present in the first place. In other words, the generator is acting as a slight brake to start with, and when the output is shorted the brake is released.

Having said all the above, this doesn't mean that I think there is no benefit from certain alternative generator designs. On the contrary.
Many years of experimenting with open magnetic system motors and generators shows (to me, at least, LOL) that it is easy to achieve a greater power output over a wider range of loads with an open system, as compared to a similar power rated conventional closed system.

But OU is a very different proposition altogether. I haven't witnessed true OU from any motor or generator system yet. Who knows, I've been searching for over thirty years, maybe if I live another 30, someone might crack it. 

I actually like the original muller design in terms of its anti cogging attributes, because most open systems exhibit very high cogging. I built a few mullers in the 1990's along with every possible variation of Adam's motor/generators. Lots of fun, but no elusive OU.

Cheers