For me, Flitz & J-B's are interchangeable. I've used both and never had a problem using them. I don't use them every cleaning, just once or twice a year, or if I notice accuracy going away a little. I did use it to help break-in a black powder pistol - gave excellent results.

as far as getting all the residue out.......I work several clean patches through the bore following the application patches (patches wrapped around a brush are great for using the pastes), then I run several wet patches with my standard solvent through to make sure everything is clean & clear. Patch dry and you're good to go