Upgrade To Conrad Johnson Premier 15?

I currently own a Conrad Johnson PV 12 with a built in phono stage which I love. However, I have read that preamps have been improved greatly in the past 5 years and as a result I'm thinking of buying the Premier 15 because it also has tubes, a built in phono stage and is made by Conrad Johnson. Does anyone have experience with it? Is it worth upgrading to?
The 15 is a phono stage only, not a full function preamp,
well.. there ya go huh?
Herman's right, but as long as you have a cartridge with sufficient output to drive the P15, it is a very fine phono stage.