Do I need a cartridge with more than .3 mV Output?

I currently own a Denon DL 103S cartridge mounted on a Linn Sondek / Ittok IV II. My phono amp in this system is the PS Audio GCPH which is turned up to maximum gain. The integrated amp in this system is the Cary 300 SEI which is driving B&W 805 speakers. When playing vinyl, the cary volume is set at the 12:00 position, when playing Cd's it's at the 10:00 position. I would like to replace the Denon DL 103S (.3 mV output) with a Denon DL 103R (.25 mV output) cartridge. I am concerned that with even lower cartridge output that I will not have enough gain available in the rest of my system. I wonder, if instead I should select a cartridge with .6 - .8 mV output or more? Any advice?
I don't know about how much gain you will need, but I can tell you that although the PS Audio GCPH sounds very good in some systems, when I used it with my 0.26mV output Benz Ref 3 Copper MC cartridge, its residual noise level was unacceptable. I could hear the noise of this phono stage 10 or more feet away at my listening seat.

Most of the professionals and dealers I spoke with said they do not recommend using the GCPH with phono cartridges rated below 0.5mV or 0.4mV at the lowest.

If you are going to continue to use the GCPH I wouldn't go with any lower output cartridge than you are already using... not because of inadequate gain, but due to objectionable noise levels.
Thank you Plato. I don't experience any noise from trhe GCPH. Perhaps it's because I bought one of the modded ones?
If you change look at the Pro-ject Tube Box SE 11. In a direct comparison with the PS and others it got a score of 45 as opposed to the PS's score of 15. See HIFICRITICs web site, look under Colloms listings.