A list of efficient speakers at ~$5K a pair.

Tekton Moab. 98 dB at 1 watt. Very full range, especially with the added, single per side, Be HF driver.

I'll third the De Capos. run them with a 4 watt tube amp and plenty loud but the sound is so nice rich but detailed

I think the reference 3a Decappo would be a sideways move against your Fritz and you might prefer the Fritz, I own a pair. Try the Ref 3a Reflectors 92 db 8 ohm they are a total different speaker but same flavor as Decappo. It’s just a speaker that could help end the chase, used you could pick up a pair in your range. I run them with a 50 watt class A tube amp.

@paulcreed  Yes, I have come to the conclusion that at the stated $5000 budget a new speaker pair would likely be a sideways move. I will research the Ref 3a, thanks.

 To all, as I stated above, I plan on keeping the Fritz speakers for the time being. 

Klipsch Heresy IIIs with titanium driver mid horns, damped, sound great and better than the IVs I owned for a while. 2 REL subs (used, cheap, perfect).