@Jorkany
First Contact wasn't supposed to be complete in terms devices being supported by OS4. It was done to get boards out to people keen to get systems out to people who were prepared to accept that not everything would be working straight away.
This isn't something that was hidden from the customer so why make such a fuss, especially when you aren't a customer.
OS4 supports multiple video cards. I have a Radeon 9250 and an X1550 in my XE and there is no problem with running different apps on both cards at the same time. You can do same with a classic Amiga under OS3. A card with dual outputs can only currently display the same image
Chris is advising caution because he doesn't want inexperienced users causing warranty issues. Most competent users will just change what they like anyway. Changing the heatsink and fan will void the warranty but I think anything else is just advice.
I would rephrase your quote above to read "Chris is advising caution because he doesn't want
Customer Support issues.", and not "Warranty" issues.
I can't believe such a big deal is being made from his comment. Since Chris and the others at AmigaKit are very busy trying to get all of the "First Contact" AmigaOne X1000 computers assembled, tested and shipped out to the First Contact buyers, plus running the rest of the usual AmigaKit business, it is only natural for him to want as little as possible new Customer Service issues, to have to deal with. I don't see anything strange in his comment.
There are some "First Contact" AmigaOne X1000 buyers who are first time buyers (like me) of any OS4.x system. This fact alone creates more support issues than normal.