I know you said you wanted to leave it there, but if I was in your shoes, the first thing I'd do is replace the sight on the MP5. The only sight that real military would use that looks like that is the C-more, and nobody uses them anymore. In the professional military of Western nations, it's an Aimpoint world, and everyone else just tries to break into the market. (I'm speaking of unmagnified optics only - there's still a lot of competition in the scope market.)
The T1 is increasingly popular among people who can call their own shots, but I think the issue model Aimpoint is still M-based. I'm not sure which generations different nations issue. I'm not sure how much it matters when you're buying a replica anyway; it's probably going to be the same guts in a different tube.
GK Backup Jacko
"Zorak's like a Long Island Ice Tea of hate." -Xaos
Personally, after seeing your AUG today with the EOTech on it, I'd leave it right where it is. I agree with Zorak though, an Aimpoint on your MP5 would look really good. Personally, I like iron sights on an MP5, but it's your gun of course.
The only MP5 I had was a stock TM MP5 SD5 real briefly which I only used for CQB, and yeah with the stock range it got having any kind of red dot sight on it was pretty useless. The stock iron sights IMO seem to work the best, and the MP5/G3 sight with the claw mount seems to be a P.O.S from what I've heard.
And as already mentioned the 552, will work on just about anything and will look good on your Aug, G36C, and MP5. I'd get another one personally.