I haven't used the Calais, but in Japan Shimano sells a lookalike reel with the magnesium spool called the 'Metannium Scorpion' (no, I am not making up this name!). In Singapore a couple of the tackle shops have brought in the Scorpion, and I bought one two months ago after doing a comparison with the Calais and deciding they were more or less identical.
The Scorpion sells for roughly 75% more than a Chronarch does (but still 20% less than a Calais). The Scorpion looks identical to the Chronarch with the exception that it's a gunmetal grey color (and quite a bit heavier), all metal, loaded with ball bearings, and has that alluring free spinning magnesium hub that purrs when you flick it.
So how does it fish? Well, the magnesium spool is smoooth (indeed), and for casting light shot-weighted flies on light line, it's the only baitcaster I own that can do the trick w/o backlashing. (Of course, you could find a quality spinning reel for $50 that does the same thing, but that's a different issue.)
And truth be told, even a gear junkie like me can't really justify shelling out the extra cash for this reel. I certainly appreciate the difference between a Calcutta 200 and a Chronarch and willingly pay the $30 more. But I'd rather have one Calcutta and one Chronarch EACH than only one Scorpion (or not even one Calais).
If you're determined to drop some serious money, the new Daiwa Millionaires have an even smoother spool than the Calais (I've done side-by-side comparisons in the tackle shops, too), and more line capacity. The drags are also excellent (so I've read). I'd want to practice cast this one up against a Calais before I made up my mind. About the same price, too, I believe.