It really doesn't matter to me whether one of them or both is wrong, I just find it amusing.
The reasons I would take communion in an RC church are the same that I would in any other church. What someone else does or does not believe does not really affect my trust in the Lord. As it shouldn't. (Although I do notice that people have freaked out when I say "thank you" after receiving the wafer).
I'm sure no one 'freak's out' when you say "thank you", but I am sure they are taken aback somewhat. I assume that you know you are supposed to say "Amen" and I wonder why you don't say it? It sounds disrespectful to me that you don't say it if you know you are supposed to say it. OTOH, maybe you are not a hypocrite and you cannot say "Amen" after the priest says "Body of Christ" knowing "Amen" means "So be it" or "Truly".
It's obvious you're trying to take the fast-track straight to Hell with such obnoxious behavior. I pity you.