SSL are feeding the ever growing army of serious project studio owners with analog processing, summing, tracking and mixing solutions.
As well as the usual channel and bus features, the XL-desk has what they call the "penthouse", a rack of 16 500 series spaces for you to put your 500 series modules in. The XL-Desk comes with the Bus compressor as standard - frankly if you are going SSL why wouldn't you want that? But the other spaces can be filled to your desires. 500 rack housings are usually quite pricey, so this could be a great way to save a bit of cash on the setup.
However, the XL-Desk isn't for the thrifty, its still got a price tag you'd expect from one of the few remaning pedigree British studio console manufacturers, wtih a fully loaded 500 space version (16x SSL E series EQ modules) somewhere in the region of £22k.