I take a Summer course in alternative firing and really like Coleman Porcelain for work that will be soda fired. You do have to cover it up as I find it grays out and looks dull without something on it. There is a local group studio near Atlanta that fires Coleman Porcelain to Cone 6, electric and gas. I never used the Coleman Porcelain for that cone, but I didn't hear any complaints when I asked about it at Cone 6. I preferred Standard 365 for Cone 6, so that was my go to.
I do insist on porcelain with grolleg rather than the US domestic porcelain. I feel that it has a translucent, luminous, quality that domestic porcelain lacks, even at Cone 6. I have recently purchased a couple of bags of porcelain that has a New Zealand clay in it that is supposed to yield translucency at Cone 5/6, but I have not made anything with it to fire yet. It came clear across the US from Washington State to Georgia, so it may not be a regular in my studio, although USPS fixed rate packaging kept the cost down (although the clay and boxes had been through a lot it appeared.
I did steer clear of porcelain for quite a time before I tried it, hearing and thinking it was difficult. Once I tried it, I did not find it so, but by then I had increased my throwing skills.