By the time Dame Janet came to record for Hyperion it was late in her career. So, yes, her voice isn't as youthful or pure sounding. But the artistry is still here. Btw, her Fauré disc for Hyperion won Brit awards, & I think rightly so. She was always a superb interpreter of the French vocal repertory--Duparc, Berlioz, Ravel, Delage, Chausson, etc. But you can't go into it with the expectation to hear a younger Dame Janet, or you'll be mildly dissapointed.
What I like enormously about Veronique Dietschy in French mélodies, which people may not fully appreciate on first impression, is that she sings this repertory in a less operatic, more cantor-like style. Which means that she never gets screechy in this music: which is something that afflicts so many soprano recordings of French mélodies that I've heard. & especially in Debussy’s mélodies, which can have a greater expressive range, & therefore sopranos can get very screechy & overblown in the upper registers, if his songs are sung too operatically. Have you heard Dietschy sing Debussy? She never gets screechy. (The only female singers that I find comparable to her in Debussy mélodies are Elly Ameling, Maggie Teyte, Victoria de los Angeles, Michèle Command, Régine Crespin, Anne Sofie von Otter, Frederica Von Stade, & at times, Claudette Leblanc, Sandrine Piau, & Anne-Marie Rhodde--although the latter three singers can occasionally get either screechy or overly operatic in Debussy.)
This more cantor-like, more natural approach also allows Dietschy to interpret more shades of meaning within the words--like an actor on stage--than a full blown operatic singer will be able to, at least not to the same extent. Plus, it helps enormously that she is a native born speaker (as always). So, I find her approach to be very natural sounding, and her artfulness in handling the meaning of the words full of subtleties. (Btw, I'd strongly recommend her Debussy & Duparc.)
Gens offers a different kind of artfulness, which is exceptional too. Although I have heard her get screechy elsewhere in this repertory, where her voice becomes overly strained, unlike Dietschy.
I should also mention that Fauré himself wanted the solo singers in his Requiem to sing their parts in more "cantor-like" manner, rather than in a full blown operatic style. Although granted, the Requiem was initially meant to be sung in a church in a religious context, unlike his mélodies. However, I wouldn't be surprised if Fauré also wanted his mélodies to be sung in a slightly more natural style that was closer to the spoken word than an operatic performance.
Though ultimately, of course, each listener will decide for themselves. But it's something to think about when listening to these beautiful songs.
