Ah, how beautiful
I happen to be the lucky fellow that is looking after Jack Giles's 16" f4.5 SDM Astrograph for a while before he puts it up for sale. It's a beauty and the first SDM built for astrophotography from the ground up. Still a stunning instrument for visual too and with recently re-aluminised primary is in absolutely as new condition.
Gonna say, I'll miss this when it's gone - put my full frame DSLR on it a couple of times and taken single second exposures and have been amazed by the results. Ah, Size Does Mater