Granite gear made a nice solo pack for about two years, didn't sell well enough and they discontinued it. I have one, and used it in my minimalist single portage mode (significantly lower volume than the Kondos Outfitter Special or the CCS Pioneer). The Granite gear Solo is really well designed but not as well manufactured as the CCS or Kondos. Repairs have been frequent.  The Kondos fits nice in the Advantage unless I stuff it to the gills. I insist on laying packs flat. I had Kondos install a grab handle below the hip belt (standard on the CCS) for ease of extraction.

I use a CCS Bushcrafter (a Rucksack with two bottle pockets) for the front pack (in double portage mode).

The "pack mistake" that I make when tired at the end of the day that makes me crazy is when I gather myself for the big heave from the ground to my back only to discover I'm standing on the hip belt.