By popular demand.

Lewm, how are they set up? Two each side and two in the center? Eliminating the electronics may upset the frequency response. How is he equalizing them? I did the same with the 2+2s. I eliminated the complex interface replacing it with one large transformer. It was favored to run up to 20 kHz at the expense of low bass. I always intended on running subs
subs so this did not matter to me. The big penalty was that the single transformer is a crazy load which few amps can handle. Even the JC1's were getting into trouble until I added a resistor in line with the primary. 
And, which of your systems gets the praise? 

Roger Modjeski designed a replacement for the Acoustat Medallion interface (which he characterized as having "serious problems" ;-) . He also offered a direct-drive OTL amp for Acoustats, as well as QUADS (the 57 for sure, the 63 I don't know).

bdp24, I wouldn't say "serious" problems but it was a compromise I did not have to make. Jim Strickland of Acoustat and Roger West of soundlabs were/are both determined to make 1 way full range electrostatic speakers. The problem is that it is virtually impossible to maintain reasonable flat frequency response with one transformer. Jim Strickland weaseled his way around his problem by using two transformers and a crossover of sorts a solution eventually borrowed by Sound Labs. Because I do not expect the speaker to do anything under 100 Hz and I can equalize any response error I can easily get away with using just one transformer straight up. 
The problem with the high voltage amps is that it is very difficult for them to develop the sort of power you need to drive the speakers with gusto even after having removed 100 Hz down. People tend to think that ESL are fragile and lack dynamic impact. Not if you drive them correctly! They will hit as hard as any horn albeit requiring a lot more power to do it. The horn and the ESL are the best impedance match to air. They just go about it in different ways. The result in terms of impact and transient response is the same but because you can use big magnets on horns they are a lot more efficient. The problem for ESLs is that there is a limit to the bias voltage you can use before you start to arc out. You could get them just as efficient if you could get the bias voltage up to say 10,000 volts but at a relative humidity of 50% they start arcing out at 4000 volts,
.Some are limited to 3000 volts.