|*Just one guy's opinion;
I have a Shaftmaster's driveshaft with Spicer joints. I purchased this in aluminum (for the lighter weight, plus it looks pretty.... but who the hell is going to see it now that it's installed...)
If I were you, money was NO object, and you wanted reliability and the lowest possible vibration-free, lowest NVH shaft..... I'd have to say 'get a carbon fiber.'
My aluminum one I have is great. No issues at all. But, I can 'hear' it when lugging the car a bit. Aluminum will transmit some NVH to the cabin.
The stock one (most likely being the best for reliability/low NVH) as you said is not an option.
A 1-piece steel would be fine for reliability and pretty darn low NVH. But I don't think you'll find anything other than stock, that will inherently transmit the least vibrations and have the lowest NVH as a carbon fiber shaft. Now, being you're 'N/A,' well you're not pushing 800hp. So I would not worry about breakages. The shaft is tucked up nice and high, so nothing would ever hit it. So reliability should be of no concern.
My opinion is carbon for the win (and Nissan put carbon on the 350Z's).
***by Ronin Z on the 350Z-Tech board;
"The 350Z's OEM propeller shaft (driveshaft) is a carbon fiber reinforced composite unit. It uses a crosswound lay-up suspended in epoxy resin. A process developed by Toray Industries, with the final product being manufactured by Hitachi."