apart from renumeration
A place i worked at once had a PPL FI. Mainly did trial lessons. Not sure if thats the norm for this type of thing, I would assume so.
It may have been touched upon, but the important thing is that anyone wishing to instruct on a PPL must ask themselves if they are experienced and competant enough to teach the varying degrees of student ability.
I am not generalising and do not wish to start a debate on the subject. In my experience a CPL (probably IR) FI with say 500 hours is probably going to be a little more in tune for this type of flying than a PPL with the same amount of hours. People may dis-agree, thats fine, it's just a personal opinion.
I was once told by a nice old chap at enstone; "you have a CPL/IR so you must be good". I replied that 'no, it just makes mistakes that much more difficult to explain'.