Also yesterday, I visited BRO and perused their Byrd offerings - selected the 4 below for potential purchase but suspect the Chandos recording overlaps one or more of the Hyperion discs - for you Byrdians, which of these are worth a buy and any to eliminate? Thanks. Dave 

I don't know the Chandos, but from looking at the track listings there are only 3 pieces that also appear on the 2 Hyperion discs -
Hæc dies,
Miserere and
Domine salva nos. In any case, they will probably sound quite different in performances by an English college choir and a OVPP professional ensemble.
The Cardinalls' version of The Great Service is pretty good, I believe - it's transposed up the standard minor 3rd which, notwithstanding my advocacy of Simon Ravens' low-pitch version above, really does bring out the contrasts between low and high scoring in different passages. I say 'I believe' because, to my surprise, I find I don't have a copy of it. My reference recording is another Hyperion, the Westminster Abbey Choir with James O'Donnell - a bigger band altogether than the Cardinalls.