I'm about to buy a good finishing trowel. Refina s*p*r*lex seems to be ok. The only question is which one. The difference in between them the thickness/stiffness as far as I'm concerned. But which one is the best. I presume the mk3/ thickest one is good for flattening the second coat as well, but as we know presume is the mother of all f..k ups. So I'd be glad to hear advices. Thx