slide in phono stage for Accuphase C-2450 preamplifier - is it any good?

Thx @lewm - you make some very good points.  

I have a MC cartridge and the Accuphase phono stage has MC load settings that are selectable from among 4 values “10Ω/30Ω/100Ω/300Ω” on the front panel of the pre-amp. 

I am sure that the optional Accuphase phono stage is well designed and built to a high standard, and it should work well.

What’s best forum may have some first hand testimonials. 

Thanks to all for your advice and input. Here is my update:

I installed a current production Accuphase AD-2900 phono unit into my C-2450 preamp. It is a substantial unit that is very well built, was easy to install and works flawlessly.

The preamp has controls on the front panel for selecting the phono stage, choosing MM or MC, and varying the MC load from 10, 30, 100 and 300 Ohms. It all works seamlessly.

It is hard for me to compare it to my previous set-up as I am using a different amp and preamp in addition to a different built in phono stage.

Suffice it to say vinyl sounds wonderful - very musically rich, detailed, fluid and engaging.