This is simply my opinion...
I think the etching primers and treatments work but are not as good as epoxy primer. In our product line as well as some others you can't use both, so be careful. If you always start with clean abraided metal there should be no reason for an etch. Epoxy primer will give the adhesion needed and actually give a little build too. Of course there are many acceptable methods but mine is usually epoxy prime, urethane prime, seal, topcoat.
As far as paint compainies...
Well I'm not impartial of course. But if a company makes and sells crappy paint nowdays, they won't last long. You can't sell to a shop anymore without having a lifetime warranty.