It seems that choir/rood screens and the designation of the "choir" as the place east of the transept where the liturgy was once sung is now pretty much abandoned, except in certain situations (monastic, academic, etc.) and in (mostly) Anglican (and some Lutheran) churches, where the choir of men (and boys) sang choir stalls. The arguments for the loft, at the rear, are principally acoustical and out of distracting (to the congregation) sight, whether or not this separates the choir from the congregation or places it with the congregation (which I'm not sure is entirely true).

Personally, I've never been distracted by the singing of choirs or men and boys from the choir stalls in (the front of) Anglican churches. Their placement, on either side of the chancel, Cantoris and Decani (usually south and north), facing each other always seemed in no way a distraction. And much Renaissance church music (of masters such as Byrd, for example, in his Great Service) was written to take full advantage of this "antiphonal" arrangement. It has, further, been a delight to sing from such a perspective (among other works, the Great Service, and, many times, the Mag. and Nunc. from the Great Service at Evensong).