Thought a quick update in order...
Ordered up an apollo neck seal to see if that would help. Tried it on and found it laid nice and flat on my short neck giving a real good surface for my silicone neck seal to rest upon. Tried my darnedest to get the neck seal to lay flat without rolling and bunching but with my short neck that was effectively impossible.
Anyhow, went for a dive and noticed that the chill had lessened a bit at first but by the end of the dive it was right back to where it had been before using the apollo.
Also is seemed as if the neck seal had stretched as it was real easy to get my fingers between the seal and my neck. So, presuming the seal had stretched too much, and thinking perhaps a latex seal would lay flatter, I picked up a new latex seal at my LDS.
I was going to trim it to my nominal 17-1/2 inch neck size (which has been my neck size since I was 18 and was what it measured when I got the suit this past April) but the Missus suggested I measure where the seal would actually sit on my neck (not that I believed there would be a difference in diameter at a given location)
Anyhow, we measured it and instead of 17-1/2" we came up with 16"!! No matter where we measured we came up with 16". My weight hasn't changed much since April, perhaps 5 pounds, but apparently my neck has changed alot! Finding a reason is a mystery for another day I suppose.
So I got the latex seal and trimmed it three rings smaller than my measurement indicated. Did this in part to give me adjustment room as well as in case my neck contiues to get smaller. Took a dive with it this way yesterday. A bit uncomfortable on dry land at first, but completely unnoticeable when in the water.
I was able to get it to lay flatter against my neck without rolling so that was a significant difference from the silicone. Also found it easier to get it sit in place where I wanted it on my neck. For the sake of simplicity, and not adding more variables, I skipped the apollo this dive.
Made my descent to 20 feet and 60 degree water only feeling the chill of the suit where it was squeezing on me. There was still a bit of a cold spot on my arm that was part squeeze and part shifted insulation...the sleeve of my jacket had shifted up when I put the suit on. As I thought about it, my rigth sleeve always rides up as I am putting the silly suit on. It's a function of the process. Tried several times and the right sleeve always seems to rid up to mid arm, right where the chill spot ends up.
There was also some chill on my chest/core but I quickly deduced this to be a bit more of the squeeze type and rectified with a little more air and a couple of alligator death-rolls to distribute the air better in the suit.
After that there were no more persistent cold spots other than my forearm, and core (correlated to depth/squeeze) but definitely not the clammy chill spot on my chest.
Best of all, after 80 minutes in the water, when I came out I was dryer than I have ever been with the only dampness clearly appearing to be condensation. And the neck seal didn't seem as uncomfortable despite being sized for much smaller than my neck.