Interesting Post Dave, I heard one of those Philips Ceramic GP390 cartridges sometime back at a little get together and I was quite impressed at the SQ.
You have got me interested now in the GP400 as they are very cheap to pick up. I suspect it is just a case of finding a decent stylus but you have mentioned Mr Stylus so I will check this out.
Might sound good on my Lenco GL75?