I love my Pearl Ex powders. I have the large flat watercolor brush and I use it for big backgrounds with PE and I use the medium brush if I am wanting to color different parts of one stamp in different colors.
I was a bit confused by what you said about the Pearl Ex and heat...you don't have to heat Pearl Ex, that is the beauty of it
The metallic pads are nice, but those you either have to let set and dry or you have to heat to dry, or you have to emboss. I personally do not like the metallic pads nearly as well. Besides the dry time, the stamps are also a real pain to clean up after you use the metallic pads.
I would recommend Pearl Ex and Versamark over Metallic pads any day...but that is just my opinion. I'm sure others will have other advice