Rvpiano, this tube sounds like a Mullard, and plays over it's price.
I believe NOS last longer. The decision has to be made as to how much of the price increase is due to rarity, as opposed to how good the tube sounds. You can get a lot of bang for the buck through tubes.
12AU7 RCA Cleartop (side getter),SPECIAL MATCHED PAIRS
New Old Stock Original Box and White Box. A great tube that rivals West Europe types, making it a great buy at this price. Some say the side getter contributes to the low microphonics of this tube. Wonderfully balanced airy highs, midrange warmth, and accurate bass. These pairs have been carefully hand selected for close dynamic mutual conductance on a Hickok 539A. I have sold dozens of pairs of these, and clients agree this tube is an incredible bargain among NOS tubes. Stock up now, this tube is vanishing from the market just like the Telefunken smoothplates!
$69.00 per pair