Yes, removing the ring wire (terminal 3) from the master socket will usually be just as good as using the iPlate. Unless it's really cheap and nasty, the microfilter provides the ring wire locally for each phone.
The iPlate does have a couple of inductors, but unless you're in a particularly noisy electronic environment the difference will be negligible.
"...stabilising the circuit"
It's not so much 'stabilising', it's the fact that the unbalanced ring wire acts like an aerial, transferring medium wave radio signals onto the line via the capacitor in the master socket. Unfortunately ADSL broadband frequencies coincide with a major chunk of the AM medium wave broadcast band.