The Prospeed does look nice. What accessories would I need to secure my Pelican cases?
Depends on what size your peli's are as to whether you need flooring or not. Prospeed sells flooring for their racks (I assume L8 offers that as part of the lineup). It's decent but I just went ahead and put chickencoop flooring on it since that was cheaper, easier to modify, etc. The nice thing about the PS rack is the ability to add eyelets anywhere along the rails b/c of the M8 sized holes. You can either get M8 eyelets (PS sells those) or you can use M8 bolts and put other tiedowns up there.
If you get their rack I highly suggest flooring since you don't want to be stepping on glass roofing back accident.
r-
Ray
edit: you can more/less see the floored area here:
Here's a shot of the flooring as it went on with M8 bolts holding down Dii tiedowns and the coop flooring: