I have purchased a few things from Dixie over the past year, and in my experience if the item was in stock when you checked out then the item is "saved" for you until it ships. So even if it is showing out of stock now the item is still in the queue waiting to be shipped.
I think a lot of people assume stainless will not rust, and as such are a little too lax about cleaning. I have a Pietta stainless I bought used and has some nice corrosion in the bore because some previous owner had this train of thought, apparently.
Stainless is of course rust resistant, not rust proof. Stainless steel still contains carbon and most certainly will rust - especially some of the "lower-grade" stainless, like I'm sure they use in these comparatively inexpensive revolvers.
As a result, I treat my stainless revolvers exactly the same as I do my blued steel revolvers, and all get cleaned just as thoroughly and timely.
As to why they are not more popular, I think part of it is that most of us that like percussion revolvers want them to be like the originals - so that means blued steel. But I think the bigger reason is that they are just flat out more expensive.
I think the overwhelming majority of BP revolvers are sold to - shall we say non-enthusiasts. I know it is hard to comprehend for folks like us who really enjoy shooting, but I'd say close to 80-90% of all firearms made throughout history have seen no more than a box or two of ammo run through them, and spend the rest of their lives living in the back of a sock drawer.
Even amongst people that like to shoot and shoot often, percussion revolvers are still thought of as nothing more than novelties or toys, so spending $500+ for a stainless percussion revolver that might get brought out to the range no more than once or twice a year just isn't practical for most of these people. For them, the $250 brass frame 1851 is far more reasonable. Therefore, Pietta and Uberti just don't make a lot of stainless revolvers because people don't really buy them.
