FWIW I have flown different examples of exactly the same model aircraft that exhibited slightly (but noticeably) different behaviours when stalling and spinning (in fact - encountered an example just this afternoon as a case in point!).
These are an aircraft manufactured in large numbers compared to most homebuilts and have been around for a long while so you would expect some consistency.
I have also read how in testing new aircraft for spin recovery there can still be surprises for TPs who have done what appears to be the same standard actions in the same aircraft previously and found that some slight variation in W+B or entry technique or minor mod to the structure/rigging results in a noticeably different spin mode.
If the aircraft were mine (and it isn't so I am offering simply my take on it - feel free to dismiss it) I would prefer to get someone who has TP training to do the initial flights. There is a big difference between having some aero training and experience and having test pilot training and experience. I do not have the later so would find someone who did for that phase.
Look - chances are very good they will find the aircraft behaves just as you expect (fantastic!) - however - if you assume that must be the case, why would it need test flying at all? Why not just strap the plane on and off you go? I mean you have carefully built it and it is a design that has many examples flying just fine - what could possibly go wrong?
Just in case it has some odd rigging problem, some slight difference from other examples of the aircraft and this difference impacts how it behaves in a nasty way, I would prefer someone holding the stick who knew how to pick that early and deal with it because that is their area of expertise. A good TP would also be able to give good info on what may cause any noticed unusual characteristics, again that is what they would have training to do - not just fly it but analyse it.
Like I said, not my aeroplane or choice to make but that is how I would see it - it is your aeroplane, you know your pilot skills and your experience and your judgement so I can only speak for me.
Ignoring all of that - wanted to say I really admire people who build their own aircraft and so dips me lid!, hope it all goes well and you get mounds of hours of ongoing satisfaction and pride from the achievement
