It's the only difference - trust me the girls will do anything for GFE except anal and msog

The standard view that I've heard is CIM with +. Greek is typically a PSE option, not GFE+ and not many of the K-Girls at these agencies will offer it -- and if they do you shouldn't be telling anyone unless they are okay with that disclosure.

MOSG it probably more a YMMV thing than GFE vs GFE+

Then again, at the end of the day it's always YMMV and so you're grandpa's wisdom will still apply.  The + is only going to get you so  far and good behaviour, cleanliness, courtesy and being genuinely considerate and respectful will often get you more than the extra cash -- especially if you repeat.  

I suspect this last bit applies to all providers not just the agencies.

I have no clue what I am, tbh.

I just don't take it up the butt.

In the DC area, with the K-girl agencies, GFE + means CIM.

I have always wondered about the difference myself.  I don't think it is just CIM because I just pay for GFE and I get CIM when I request it.  My guess is MSOG with the first shot being BBBJCIM and the second shot being sex with the girl.  I would ask the girls but their English is usually limited.