Until I found AG, all I used were OTC products. Meg's Gold Class served me well for years on a number of cars, as well as Lexol. A few years ago I had a problem with dye transfer from my wife's red leather jacket on the tan seats of her Rendezvous. Neither the GC or Lexol would remove it, nor Simple Green at 1:4, so I tried Tuff Stuff liquid. Bad move! It removed most of the dye, but also the coating on the seat. That drove home the principle of trying an unknown product on an inconspicuous area first, as Tuff Stuff aerosol had never caused any problems. Based on that one experience, I would be wary of any product not intended for leather. Nowadays, I use Leather Masters once in a while and OPC /OPP regularly. I still use the Meg's GC on the leather wraps of my pool cues. It cleans well and leaves the leather soft without being slippery.
Bill