The Henry AR-7 have many problems, not like the old Armalites. Before you buy, read up on them. A friend had one and it was the biggest POS. The Marlin Papoose is nice and can have a floating case. But for me and if I was wanting a take-down semi I would go with Ruger's new TD.
As to lazi's Kel-Tec, they fit in a back pack great. Wish I still had my 9mm one but since I don't have a Glock any longer I did not see any reason to keep it.