The mix of carbon fibre and aluminium is actually what appeals to me about them! I didn't realise how popular they are, had a few good offers for the frame already, although there's no way I'll part within it...
I'm doing a modern build of mine too. Had originally intended to do a retro build with original Z1's etc, but I reckon the STS's were a bit ahead of their time and a complete new build would do it justice. Have managed to keep the whole lot under $1500 so it compares favourably to the complete new bike option.
Just out of curiosity, how much did you get the LTS DH for (if you don't mind me asking)? You should check out www.betd.co.uk
They make a replacement bearing set which makes a huge difference to the function of the rear suspension and also sell replacement shocks if you ever blow yours (annoying thing about the STS/LTS bikes is they rely on a specific shock mount).
I reckon the 1x9 is a good move, the LTS DH wasn't really intended for a triple crankset so the single chainring will be more in keeping with its downhill origins!! Is that what you'll be using it for?
1997 Giant ATX 980
2007 On-One Inbred