Never heard the Radio 3 review but if it was the DG Bernstein VPO Mahler 5th being referenced (as distinct from the good - not great - earlier NYPO one on Sony) I'd say don't hold back - it's fabulous: a highlight of probably the most emotive and fascinating Mahler symphony cycle on record.
Personally I'm much less enamoured of the Rattle set, but then I've never really been a fan of Rattle anyway, his Sibelius and Second Viennese School recordings excepted.
And what - only nine Mahler Fifths? You need far more! Try Haitink's Concertgebouw Fifth (Philips, now Decca) and, if it's his DG set you already have, Kubelik's 1981 live performance on Audite - my personal favourite interpretation of all the Mahler Fifths I know. Rafael Kubelik was a consummate Mahlerian and his live performances are even finer than his excellent studio recordings.
And if you can trace it, download Willem Mengelberg's Concertgebouw 78 of the Adagietto - one of those wondrous old records that has never been bettered IMHO. I wish he'd recorded the whole symphony.