Gotchas for calling OPM programs from ACTGRP(*NEW)

Hi folks, 

I couldn't find sufficient discussion on this in the archives, so after a 
couple of hourse here goes here.

I've always done my non-default activation groups, binding etc., in situations 
where I could program a call to a program with ACTGRP(*NEW), and then 
ACTGRP(*CALLER) from there, in general. 

However, I have a new interactive program call that I need to bind with a 
service program (or two or three maybe), with procedures and so on, but in this 
interactive report front-end I'll need to call existing prompting programs 
(listing available values and so on and returning the selection, for example). 
These existing programs in some cases are OPM programs (RPG-3). 

The overrides in the bound set of programs, in their own *NEW activation group, 
will generally be there of course, and overrides in the OPM programs called 
from there will have their own, and overrides can cause a mess. 

                Question: What are other gotchas to watch out for? 

And another question that came to me, is, I have seen IBM documentation on the 
API programs to the effect that it's okay to call an OPM API program (such as 
QSNDDTAQ, I noticed) from an ILE non-default activation group with no problem. 
If there are non-override gotchas as an answer to the first question, what 
might be gotchas to any of the APIs.

And/or does anyone have experience with this mixed scenario? 

.....Fuggeddaboudit answers are accepted with some chagrin....

--Alan