I agree with alot of what you're saying. To look at any particular snake and say it is definitely a hybrid by appearance only really shouldn't be done. In some cases, you can be 99.9% correct in calling it a hybrid, but there are many instances that you really can't be 100% sure. The cases of ultra, anery C and frosted being excellent examples.
There have been some excellent points brought up in those discussion threads. The most convincing is that if those genes originated in non-cornsnake species/subspecies/whatever, why haven't those genes been demonstrated in "pure" specimens of those species/subspecies/whatever? In the case of frosted, I think it has shown itself, but it has also shown up in "pure" corn lines as well. I actually think the frosted look is exactly that, a look that has been selectively bred for but can also just "happen", very similar to the zigzag/aztec pattern in how it reproduces itself. I've seen corns and intergrades/hybrids alike with varying degrees of frosting.
Carol pretty well explained why some of her anery C's have a higher saddle count. Yes, I agree that it can be an indication of an intergrade/hybrid, but again, we shouldn't say it is a 100% guaranteed indicator. It has been shown that other factors can create a higher saddle count in certain individuals. I have a couple of corns that have a higher than "normal" saddle count, but who is to say what is "normal"? You could probably take all the saddle counts of all the corns in each breeders' collection, come up with a bell curve for each breeder, then compare them to each other and create yet another bell curve with certain breeders being at each end strictly because of the number of related corns in their collection. Carol's particular bell curve would probably be very wide as she has both her higher count anery C line as well as her banded/milksnake line with it's much lower saddle count.
And in all honesty, who can positively, 100% guarantee, cross their hearts and hope to die swear that each and every cornsnake in their entire collection is 100% pure, never-ever, not even 100 years ago had a single non-corn gene enter the bloodline? I sure as heck couldn't! I've had several wild-caught snakes in my collection that now have their genes mixed into multiple individuals/lines in my collection. Rich himself has gotten many snakes from the wild over the years. That's where many of the genes we now have came from. Can Rich swear that any of those snakes didn't have a single black rat parent six generations ago? How long has it taken to find and identify all the currently known genes? And we still haven't found them all. I really don't know if the other rat snakes have been as interbred as cornsnakes or not. For all we know, there may be the lavender, anery C, caramel, whatever genes in those species as well. We just haven't isolated them yet. We already have similar genes in other species, such as anery and hypo Hondurans. Could they be the same gene? Maybe. We have color mutation hybrids already so we know that something must be compatible somewhere.
Trying to boil everything down, IMO, arguing over what is a hybrid, an intergrade and a pure corn isn't going to matter much in 500 years. Look at how much man has altered and varied the dog over time, and he didn't have all the other wonderful species to breed with it. We are able to mix cornsnakes, kingsnakes, milksnakes and who knows what else into the pot! Sometime, somewhere, someone is going to hatch out the robin's egg blue "cornsnake" that is my heart's desire! I just hope to be alive to see it.