I don't have any technical knowledge to offer, however I'm also building an electrostatic setup and went through something similar.
My budget was a bit higher, around 13'000$ and for the time being I settled for a pair of SR-009 and a Woo WES and still need to decide on a DAC
I was pretty sure about getting the SR-009 but I was completely open for the amp and I must say that it wasn't an easy choice, I'm from a country where if you want to listen to something you have to buy it, import it and listen to it for yourself, so when I buy something I rely purely on online forum and reviews.
I was actually surprised of how little the choice of electrostatic amps was, I originally decided to go for a BHSE but when I realized that there was almost 1 year waiting list and that some people were complaining that the combo SR-009+BHSE was bright I decided to move on.
This is when I posted a listing on headfi saying I was looking for an amp, I did receive a couple of offers from people offering to either build or sell a KGSS(HV) but when I realized that those amps were not commercially available, I quickly moved on, I mean the people seems reliable but let's face it there's no guarantee that a guy building amps in his garage now will still be doing so a year from now and if anything happen, there's no warranty and I'm stuck with a custom built amp in a foreign country, finding someone to repair it will be a pain, I also figured it would be harder to sell if one day I decide to, I'm not saying it's true, it was just my logic.
So I settled for the Woo WES, from what I can read in this thread maybe it wasn't the best choice, but there's also a lot of press online suggesting that the SR-009+WES is an amazing combo, Woo Audio has a good reputation, warranty and they build and deliver in 3 weeks, I do agree that they are overpriced, I also tried to get a discount from them if I was taking a WES+upgrade+SR-009 and what they offered was laughable.
Hopefully this will help a bit.