I currently have the 6505 1992 Original and new straight cab loaded with the 1230+ speakers at my house. Rendering and uploading my initial impressions on it today.
Much like with the 6505II that I was able to demo in late 2021, the amp tone is largely unchanged. I noticed a slight bit more clarity and focus in the upper mids, we're talking very slight. Everything else we all know and love (or hate) about the 5150/6505 tones are still in tact.
Is this a marketing move? Absolutely. Was the switch to the Invective transformer so that they can use the same transformer across their flagship amps and make it a cost saving measure? I'm sure that it was. But, in talking to John Fields, he put a lot of time and energy into making that transformer as close to, what he felt, was the best of the original 5150 transformers they had in house, and then tweaking it for slightly more clarity. I believe every word, because John has been extremely forthcoming with me about many things going on over there, and he hasn't pulled any punches. He's an amp and speaker lover, and a fan. He is not a marketing guy in the slightest.
As far as the 1230+ speakers, I'm already a fan. Not sure if any of you played the old 1230 speakers that came in the VTM/Butcher cabs after they stopped using the Celestion K85 speakers, but they were honestly a great sounding speaker. When Eddie came over, they essentially used the 1230 and changed out the cone for a greenback cone. The early ones, according to John, were some of the best sounding speakers he'd ever heard. But unfortunately, sourcing and manufacturing inconsistencies made them sound wildly inconsistent throughout the years. A lot of them sound REAL BAD. I have a 5150 slant right now and it just sounds fucking terrible. But I had a couple recently that didn't sound bad at all.
The 1230+ has a tighter low end, strong low mid voicing, and has the very top end fizz tailored a bit. The old 5150 cabs enhanced the 5150 fizz. The new ones dial it back just enough to make the amp sound a little more organic. I truly think they are an awesome speaker, and I generally don't like non-Celestion speakers.
But, that's just been my experience. These will be in the wild soon, so many people will be able to form their own opinions.