I'm not saying that using "A" is right, just that "A" often has been used by a lot of companies, without anyone taking much notice.
I don't like any of the suggested AmigaOne names - they're too long
Yes. I just tried typing all of the various Amiga models in to google, using the "A" prefix instead of "Amiga," and only A600 and A1200 brought up any mention of the Amiga. All of the searches returned plenty of computers, phones, tablets, cameras, etc. The first page of A500 not only didn't mention Amiga, but did list the A500 road in Staffordshire and Cheshire, England.
Honestly, this is way too much fuss over one letter. This thread has been going on for three weeks now which far exceeds the impact that any naming scheme will have.
I personally couldn't care less if Apple sold a Mac A4000, unless they called it an "Amiga 4000" or "Amiga A4000." It wouldn't be unethical, amoral, or "parasitic" in the slightest. Likewise, an "AmigaOne A3000" will never be an "Amiga 3000." Having said that, I'd suggest using a different number like "AmigaOne A3041" just to avoid confusion when people inevitably shorten the name in discussions (personally, I'd shorten it to A1-A3041 for clarity, but I'm not everyone).
Hans