No worries Gav, a lot of it comes down to personal preference too. Don't worry if it is not 100% perfect, there will always be a skim of filler on pretty much every panel. I am a perfectionist too, but I can only get it so close before I run out of talent! I just wasn't happy with the level of distortion I was getting from oxy and found I could minimise later work by making the patch as correct as possible and keeping it as cool as possible while welding it in. Each to their own, and I am impressed by the level of skill the TAFE teachers have after oxy welding and planishing in being able to get panels pretty much perfect, something we can all aspire to. For surfaces I can access I am using POR15/KBS too, it was only things like the sills and rear hatch that I will be using the fish oil (after painting, of course ). Another thing to keep in mind is that I don't think they let you own acetylene bottles, but you can now own argon ones, so rental gets expensive.
Keep up the good work.