This has been a very helpful thread. Let me share a bit of my mindset both as therapy and in the off chance it is shared by others on this board. I have the resources to buy a monitor in the $3000 range, maybe even two. But it would be a significant purchase for me and I don't have the time or money to be buying and selling them until I find the right one. I am not a professional musician but do play regularly. Tone is very important to me as it is a key source of my own inspiration. It's also important to me that the sounds I make are pleasing to others. This can be accomplished with a very wide range of equipment.
However, I also appreciate fidelity. I am not an audiophile (although I do enjoy audiophile grade equipment), and I am not a professional sound engineer. But I can quickly say what I like and what I don't like. As many have said, with traditional guitar rigs, you get a pretty limited set of options within which to work. If you don't like it, buy another cabinet, try a different head, grab another stomp box (although I'm not much of a stomp box guy). I've never really had to concern myself with the accuracy/transparency of a speaker. Even colored sound can sound "good". But what I want here is complete transparency so that I'm not worrying about dialing out coloration. I "believe" I've found a decent option here in the sub $1000 JBL612. But I don't know if I'm right. I am not experienced enough to trust my own judgement in this regard.
I look at high end powered solutions from EAW, Meyer, Turbosound, RCF, and L-Acoustics and think that surely one of these has achieved something approaching the transparency of Jay's design. But there's no way to tell.
In the end, this differs little from the quagmire of guitar amp/effects options that exist out there. But somehow, the potential excites me to the search again. I have in my mind the idea that if I can find the most accurate and transparent speaker out there and match it with the Axe-Fx, I may be done with the search once and for all (at least until Fractal releases the Axe-Fx II!).
But Scotts, you offer good advice. I'm sure my frenzied research will subside soon and I will settle back into enjoying the music.