I just bought the H9 P-51 in an ARF version. If all goes well I will maiden her on Sunday. I will let you know how it goes.
Some would say the PTS P-51 is a good first trainer and some would argue against it. Most of those arguing one way or the other have never actually flown one so I will reserve my opinion until I have actually flown it.
This will be my third airplane and first taildragger.
If what I have read is true you may consider the PTS Mustang as a viable second airplane and with the release of the ARF it is now more cost effective.
I do agree that no matter how comfortable you feel with your trainer get on a buddy box anyway, better safe than sorry.
PS: Millington brings back some memories, I did my A school there way back when