The original shafts are no longer made, only available used to my knowledge. They used slightly different materials and construction techniques vs. the newer shafts. There are also, I believe, multiple versions of the original generation shafts - "pre-cat" vs. regular, having to do with the logo on the shafts.
In theory the newer version is better technologically, and it does have slightly lower deflection, but there are players out there that swear by the original version and go out of their way to find more.
Without prior experience of the older shafts, I would stick with the newer version - more updated, in warranty, etc. If you have doubts, you could always buy both, or buy a used 314-2 and a used first gen, then just sell back what you don't like and not lose much if any money at all.
Scott