I sat in a van with a RIB and a poptopuk bed and i couldn't sit up straight, i'm only just 6 foot. I know the RIB is a high bed but they also had a 'normal' bed there and it was the same. A definite no no for me. The top of the bed is along the same profile as the top of the van, so you lose the thickness of the bed as head room. The difference between the slimline and the normal didn't aid the space, so I don't know what is in the space in the normal one.... Had an Austop on my previous van and a RIB and could sit up sttraight.
The allen bolts for attachment to the hinges and gas struts are on the outside of the poptopuk also. Looked a bit 'industrial' to me.
If you're spending £5k on a bed, get an SCA I would say. Or save yourself money and get an Austop which is what i'm doing. The difference between the two seemed minimal, if anything the Austop one better.
Andy