Ok so the mod is now complete. I soldered in the mills resistors this evening, and while I was in there I added dynamat to the driver baskets and applied mortite to the driver-baffle mating surface.
The difference is stunning. I will say that I've been running with the new caps for about a week now and haven't been blown away totally, but with the addition of the new resistors i am SHOCKED. I've listened to several songs that I know very well in the last hour or two, using two different amps (Hafler DH-220 and a Carver TFM-25) and with both amps there is just a ton of little details in the music that were never there.
The vocals did seem to move back in the soundstage a bit, especially on the Carver, and the stage is wider with both amps. I can also hear a lot more 'SDA magic' than before.
Bass has more 'slam' than it did before. This is of course even more pronounced with the more powerful Carver amp, but is noticable with either amplifier.
In the middle, I get more sense of realism. This is especially true in percussion instruments and guitar plucks. Instead of a 'muddy' sense of when a key or drum was struck, drum hits and guitar plucks have more crispness about them now.
All in all, I'm very pleased with the mod.