Amazon.de has the 5-disc set listed for 99 Euros. Those 2 additional discs would have to be rather extraordinary. Nothing remotely comes to mind that would justify the additional cost. Nonetheless, I look forward to Neil's announcement, when he gets clearance!
Not sure it would justify the cost though I might be enticed to pay - some live stuff from that period. The spring '73 pre-BSS europe tour where they filmed/recorded the documentary - did some stuff surface from that? More from the 73/74 tour?