I use the 1974 Graduale Romanum, as it is what both my abbey and schola use. I actually use the Graduale Triplex which is the Graduale Romanum with the neumes of Laon and Saint Gall above and below the square note staff. It helps fine-tune interpretation of the chant. It is adapted to the post-Vatican II liturgical calendar, and also includes the monastic propers.
There is nothing wrong with the Solesmes method, it is the predominant interpretation of chant. Our abbey uses it, as does our schola. I know at least one abbey in France that leans more to the Pothier style. It’s a complicated subject on which much ink has been spilled! FWIW the Vatican has entrusted Solesmes with the job of preserving and restoring to use the Gregorian chant patrimony of the Church, a task still very much alive. In 2005-2009 it released 4 of the 5 volumes on the new Monastic Antiphonary (for the Monastic Divine Office post-Vatican II), in 2008 it contributed the music for Les Heures Gregorienns, a diurnal antiphonary for the current Liturgy of the Hours, and in 2010 the first volume of the new Antiphonale Romanum which will be the official chant antiphonary of the LOTH. The current volume, labelled Volume II actually, covers Vespers of all Sundays, feasts and solemnities. Our schola uses it when we chant solemn Vespers at the cathedral in Sherbrooke, Quebec.
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