Here I am.
I first heard the ART1000 at Cymbiosis on an Aro. I was coming from a Kandid, which when I picked I preferred over the XV1s by quite a margin. When I compared it to a wide range of cartridges on that day I preferred it to everything else - it’s the only one that actually made me stop and think I was listening to something special. It sounds real, is the only way I can describe it. I thus purchased one which has been on my SE for about a year now.
Re: the phono stage, I am pretty sure the demo was with an Urika (it certainly was with the same phono stage for everything), so it shouldn’t be a terrible mismatch. That said, like other AT MCs, when it comes to Naim boards, I think S loading is better than K, which would also imply that it shouldn’t use the exact same loading as a Linn cartridge.
When I realized I was going to move away from the Kandid I sold my Urika as I did not want to feel trapped by a single loading option, so my experience may not be completely enlightening to you.
I’d encourage contacting @Cymbiosis for thoughts on this as Peter would be sure of what’s what when it comes to this.