How long should Pre amp (12au7) tubes last in Rogue Preamp?

I'm no expert but I always thought driver tubes are not run very hard and should last like two or even three times as long when compared to the amp's output tubes (which run anywhere from 2000 to 6000 hours depending on how hard you drive them and their bias setting).

from the FAQ page on Rogue's website:

How long do the tubes last? 
Preamp tubes and the small tubes in the power amps typically last at least 5000 hours before they need to be replaced. The larger power tubes in the power amplifiers depend somewhat on how hard they are used. "Typical" lifetimes are about 3000 hours which equates to about 3 years if used for a few hours every day.

http://www.rogueaudio.com/FAQ.htm

@aberyclark,
Those new Gold Lion 12AU7 sound amazing. Replaced some new Mullards with GLs and am very happy with what I am hearing, especially the vocals and strings.

I've always heard preamp tubes last up to 10,000 hours.  Are you wanting to change something in the sound or tonal characteristics?  If so, what is it?  

No, just curious. The tubes are fine. I like how they sound...just curious thats all. When it is time to replace, I may try the Gold Lions only because many owners who own the RP-5 say the first thing they do is switch the tubes and talk about a night and day difference over the stock JJ's.