A few newb/background questions about the XKL TOAD

There's recently been a lot of talk about the XKL TOAD, and I, as an interested lurker had been holding my tounge, despite having some questions. No more. 1. How does the XKL compare with the Jupiter? Given that they both had features like an extended address space, was the XKL basically a "if DEC won't build it, we will" type of thing? 2. What the difference between the XKL TOAD and the various SC systems? Was SC a reseller/packager/intergrator or did they have their own seperate "Super KL"? 3. Does KLH10 support any of the XKL extensions? 4. Do the freeware copies of TOPS-20 floating around the internet have any support for these extensions or were those proprietary to the copies of TOPS-20 that shipped with TOADs? Thanks for answering this barrage of silly questions, Mike