Since this thread is resurrected, I think it might be useful to highlight something that I have fully realized in the interim years. With the Extrema’s, one is severely limited to the amp one can utilize. That amp needs to be a large powerful ss amp, or maybe a pair of huge CAT amps ( I can think of no other tube amp that could drive these!). This limitation, which was briefly mentioned before, was not really highlighted. I had somewhat realized the issue, but was not as cognizant of it until a fellow a’phile bought a pair and had a very hard time matching up to amps that could do the speaker any justice. In the end he had to buy a massive and expensive ss brute.
The GH’s OTOH are not that difficult a load, and as such a number of great tube amps can work well. This, IME, is a major factor when choosing a speaker, more so than I realized before. For example, the new Estelon Aura’s, sound great...BUT if you read the Stereophile review and the follow up by JA, they are an absolute bear to drive!! Easy pass for me given this.