I am in the process of building a set as well. I went ahead and purchased the zoom eyepiece along with 2 30x eyepieces. I haven't built up a bracket for them yet but I have put the 30x WA and the 20-60 zoom side by side to compare. I'm looking forward to getting them setup. Planning to start putting the bracket together this weekend
The 30x WA is crisp to the edge and with good color resolution and clarity, very impressed with this eyepiece so far. It really does make FOV of other eyepieces or your binos seem a little constricted.
The zoom is a shade "darker" and really only retains good clarity to 45-50x. Still very usable and I will keep it around for digiscoping or backpacking. Even still, I believe the 30x WA is going to be very capable for most applications. I have no experience with the extender/magnifier.
The pair of scopes alone weigh right around 5.5-5.75 lbs so depending on what the bracket ends up weighing, I am hoping for sub-6.5 lbs. The reasons I went this route for big eyes are 1.) ~$2,600 for Twin Kowas vs $5k for highlanders, $5k for twin swaros, $4-5k for btx. 2.) Straight viewing. 3.) Weight. The only competitors here would be the BTX 95mm and under and the twin swaros. The twin Kowas should allow me to keep using a lighter weight tripod under normal conditions.
I think Hatchet Jack on here has a set and could provide some insight as well.