If you're going for the aluminium SRA5108, as I did, there are two things you might want to be aware of
1. It has a maximum load capacity of 6kg. Givi UK have told me this is the maximum load that can be carried inside any case fitted to the rack, but this is not clear in the supplied literature.
2. I have a Givi E52 Maxia top case. It sits very close to the pillion seat when mounted on the SRA5108 making the pillion's seating position very cramped. I don't know if other models of Givi top boxes have the same problem on the SRA5108. I wish I'd purchased the SW Motech Adventure rack which appears to have alternative positions for the Givi top box mounting pins which look like they would give the million seat a bit more room if needed.