Having worked with sports rehabilitators, sports therapists and remedial instructors I feel that they all play a vital and valuable role within their remit. I was luck enough to start specialising early when I qualified but when you compare some physios who have spent a couple of years rotating to someone who has specilised from the outset there is little comparison.
The only thing I would say is that those who I have worked with who did not qualify as physios, and thus did not do clinical rotations within the hospital setting (seeing neuro, cardiac, respiratory patients etc..) tend to be able to pick up that what they are assessing does not fit the picture, but not always what the cause is....then again a lot of physios don't always!
I hope that in the future the HPC regonises professionals for what they are and the role that they play.