I have a P8 - it is an excellent turntable for the money and as with all Rega's isn't something you can upgrade as easily as other brands (VTI, Linn, etc.). I expect the P10 is an upgrade specifically because of the tone arm.
I chose the P8 over a Linn because it meant I'd have to replace the table if I wanted to upgrade anything beyond the cartridge and phone stage.
I know myself and frankly bought it to enjoy the several hundred LPs I have and recognize my analog system is used 10% of the time and is more about the engagement. My digital and analog sources are approximately equal in sound quality.