It is logical that with less types there is less T&E to be done. It is clearly important for the reasons already highlighted. Ensuring the kit we have is safe and effective, meets UK regulation & standards and having control of our own defence. Effective T&E by competent and qualified flight testers could save money and makes us more flexible to emerging threats.
I think you should stop comparing the Chinook 3 with the MH47E. The NAO report said the 3s were unique aircraft. It is an easy mistake. A K model Herc is a very different aircraft to a J Herc, but they both look very similar from the outside.