There are 3 versions :
Prière is in the book of "Six Pièces" by Ropartz (as are the Fantaisie and the Prélude funèbre). It has quite a "Franck's touch", as many Ropartz's organ pieces. IMHO, it's a good deal above standard Prières as so many were composed at this period.
There is still another prière in the 6 Pieces : Prière pour les Trépassés which is also fine music.
The aim of the 3 versions is to compare three organ sounds (files have been normalized in level). All which follows is pure personal opinion :-)
IMHO, Metz (which is a later Mutin and not a Cavaillé) sounds clearly Mutin rather than Cavaillé-Coll : more "stringy", heavier and less refined, less poetic (matter of taste).
Caen is Caen as always, beautiful and smoother than Metz, but less "round" than Oloron.
Oloron is, IMHO, a fantastic sampleset. With it, I find back the exact sensations resented when I had the luck to play some real and "intact"Cavaillé-Coll in the 12-30 stops range.
Congratulations to Mr Grabowski for this stunning achievement !