Thanks for all the info!! If a Suhr RL comes up used on eBay I might just call it a day, ha! (Have had it before to good effect, along with the two notes captor; pricey though they are, so is my time if I spend several days planning / building my own iteration)..I'm just wrapping mine up, and doing the "more accurate" version is a total PIA build wise. The reason is that you want to have each of the inductive elements mounted at 90 degrees to the others in order to minimize mutual inductance, which for this project is a big deal. Obviously the inductors themselves, but also the power resistors if not using the more expensive non-inductive parts.
All to say, I'd recommend building Freeman's recipe for the simple version and call it a day. Someone in the thread says they have both versions and the differences are slight when playing them.
So back to mounting inductive elements at 90 degrees to each other, with the simple version you have three inductive elements, the two inductors, and as a group the wound power resistors. You also have the X, Y, Z axis to mount the three elements and spacing of them is not so critical (though more spacing the better). Add the extra elements of the "more accurate" version and you still only have X, Y, Z axis to work with but you have 4 inductive elements, therefore spacing at least two of them becomes a big deal.
Try to implement switchable main inductors in order to move the LF peak, and the physical layout becomes pretty hairy. I had to resort to iterative tuning of the physical spacing of the LF inductors placed on axis in order to leverage mutual inductance. Plus had to do the layout to get enough physical space between the two HF inductors placed on the same axis in order to keep the entire layout in compliance with the three axis principle. Total PIA for very little improvements. So build the Freeman recipe IMO.
That said, I would not skimp on the cap(s) for this design though I have found the lower priced 20awg inductors to be quite satisfactory even for 150wrms (sine) designs. If you go with lower priced inductors, be sure to model the design in SPICE in order to adjust the damping resistor values to compensate for the differences in internal resistance between the premium parts and the lower priced parts. If you need/want help with that, just post your inductor specs and I can model it for you and give you the revised damper resister values....
Personally I'm liking the latest from Own Hammer. I'll be shooting IRs of my homebrew 2x12 (a 1936 but 1" deeper) loaded with G12T75 in a couple of weeks. But I'm not holding my breath after hearing all of the DIY IRs floating around the net. There is an art to get something usable and LOL, my guess is I will be way off the mark even though I have great gear to capture the impulse... That said, would be happy to trade IRs with you and we can see how we did!
Regarding IRs, I have done a lot of testing to figure out what is important and what isn't - there's definitely a slight art form to it. Having a somewhat anechoic room, mics you like and good pres seem to help considerably. Unfortunately my current music/project space is small and untreated so shall wait and see how the next set turn out with the new 4x12. Will post a g drive link to the result IRs later next week, provided they aren't terrible.