I found the other way. The bulge on the SS messed with the angles slightly.
Thank you for your help, your answer is crystal clear and I finally took this difficult decision by following your advice and explanation! I'll go for the KAI with Japanese handle first, and then in the next months I'll look to expand my collection with a feather model, probably the ss itself (just out of curiosity).Not too long ago Feather only made the RG and DX models, and they had a big following here on B&B. Wet shavers had no other choice. Today I think many of those seeking a shave closest to a "real straight" - whom have used all models - prefer the RG and DX to the newer SS model. I think part of that is the head design.
Your experience may differ, but if faced with picking one I would suggest the RG or Kai. There is also the cheaper Korean CJB.