SATA 'backplanes'

[L. V. Lammert]

Looking to rebuild some servers, .. seems like these 'SATA Backplanes' 
would be better space wise over individual chassis (tower cases, not rack 
mount):

        http://www.startech.com/info/downloads/mobile_storage_line_list.pdf
Is there any downside to these? Planning on LSI/Megaraid controllers for 
compatibiilty (any recommendation for 4 & 8 port?)

        TIA,

        Lee