You are. Although those of us who believe the doctrine don't care for the term 'sinless perfection' much, since it holds all sorts of negative connotations for many people. We tend to prefer the terms 'entire sanctification,' 'Christian perfection,' or 'full redemption.' Some use the term 'baptism in the Spirit,' although they understand what the baptism in the Spirit is wrongly, saying that it does not occur at regeneration, but comes later.
So, does that mean sinless perfection, regardless of what connotations it brings up?
From all my dealings with them, they don't believe that 'baptism in the Spirit' is a perfecting event either. It doesn't seem to have the remotest resemblance to the doctrine of 'entire sanctification' - to me. (I believe the indwelling/filling with the Spirit occurs at the moment of salvation, so that in effect puts me in a second-class Christian caste according to the 'baptism of the Spirit' folks...)