I know what you mean about a D.Jing playing a record if he's paid cash for it over a freebie, but I actually disagree, especially if you are talking about an exclusive - You gave a few D.J's a Kent D.J copy of 'Little Anne - What Should I Do' (with a covering letter) a few months before it was released, and I remember Soul Sam playing it (as I'm sure others did) I also played it at The Embankment Club (which was your intension by giving me a copy) But I do agree, the moment anyone can get a record, a lot of D.J's lose interest in playing them - A crime really, but we all understand the thinking behind it.
I think a longer gap between giving the D.J's the D.J copies to play as their exclusives would keep a new discovery 'out there' longer. The timing of the general release could coincide with the D.J's shelf life of that record, then it would hopefully transfer to other D.J's as their new sound to play which would be recognisable, so an instant hit for them.
All the best,
Len