Micro Seiki MA 505 Arm - how good is it?

I have a Micro Seiki MA 505 Mk I arm on my Spacedeck. I am wondering just how it rates against more modern - and expensive - arms such as, say, a Kuzma Stogi Reference, a Graham Phantom, a Triplanar, an Ortofon, or maybe an SME M2.

The arm is being used with a 15g AT headshell and extra sub-weight with a Koetsu Rosewood and the sound is truly excellent. It certainly sounds a lot better than the SME IV which it replaced (which sounded boring with just about any cartridge I tried with it). The MA 505 is also more versatile and by using different headshell weights I am able to use a wide variety of cartridges with it.

The real test of course is how it sounds, and it really does sound excellent, and I have nothing to complain about, as I did when I had an ARO on my LP12 (sounded thin and lightweight) and the SME IV (boring). And yet I have a nagging doubt that I should be spending a lot of money on a more recent arm, particularly as the MA 505 was not even one of Micro Seiki's "high end" arms.

I'd be interested if anyone has any thoughts on how the MA 505 Mk I compares to more recently produced and more expensive arms.