I have used all types of Zimmerit, whether it be Resin, Brass, or Putty. I could see how Tamiya's Panther G with Zim would be tempting, especially for those who struggle with applying puttied zimmerit. Photoetched Zimmerit is very easy to use, and all you'll need is superglue or epoxy glue to apply it. I prefer epoxy glue because it gives you a little working time to make sure the Zimmerit is flush to the surface and even. The only downfall in my opinion is that is looks a little to uniform, and sometimes the ends of the Zimmerit sheets do not meet up perfectly flush at the corners (especially on the rear).
Also those Tamiya kits packaged with teh Zimmerit are a little pricey, and if you prefer prefabricated zimmerit..to go the Cavalier Resin Zimmerit Route. It is alot less uniform, and looks alot better then photoetched brass Zim.
I know you said that you have tried puttied zimmerit. Why don't you like it? It took me a long time and practice on scrap models and sheet styrene to get it done. But I wouldn't use anything else. i have tried all types of putty..from Milliput, Tamiya Basic Putty, to Squadron Putty. But nothing beats Tamiya's Polyester two part Putty. I learned how to do it by looking at how the Japanese modellers in Armor Modelling magazine had done theirs. The Tamiya Zimmerit Application tool is very easy to use and ensures your zimmerit is to scale. Moving it through the Polyester Putty is very easy and it hardens like an epoxy. I recommend checking it out if you can.
Cheers
Rob