Have a "few" sets of these in various condition. Based in France / EU though.
From memory, Zircal alloy spokes appeared later, in what was said earlier probably the Mk 2 version (or perhaps even later since I have seen some versions with "Mk 1" hub changes with the steel traditional spokes).
The XL version had solid round spokes. There is a version with bladed spokes too, which I'm prettys sure were branded with the name SL, I believe that was a fraction bit later. Black is most common.
The rims with cut-outs though with extra machening to near death are SL SSC and were / are more common in silver finish with bladed spokes. SSC being Special Service de Course - ie. top end race day wheels. In my experience, it's these that crack near the valve hole on the rim internal channel.
It is shocking when you find it's actually going on under a bar-code traceability sticker too.
At the end of day, IMHO, these are all one of the last and best 26" high end ultra light and ultra rigid wheelsets with some niggles and the freehub does need regular maintenance to last.