Have just had a look at the article and dug out the original prints and the Kentona in cooltone really is a lovely blue black. The magazine repro is a little bit lighter and a touch more cyan. It's always tricky with these sort of tests as the reproduction will never be exact for toned black and white prints unles accurate scanning and extensive proofing is done which would only happen for a fine art book and not for magazines. The worst occasion was something similar I did for the BJP. The same image processed through cooltone and warmtone dev came out almost the same murky grey in repro. And all the supplied prints were reproduced about a stop too light!
I have tried adding Benzitriazole to different developers and have got some very nice 'cold' prints but still nothing like the Harman Cooltone, which with MGWT, Forte and a few others gave such wonderful blue blacks. One day when I've got time, I'll get in the darkroom with lots of formulae and raw chemistry from Silverprint. Then I can sell the powder developer as 'Crawford's Cooltone!' Actually, this makes me think. It was discontinued I believe for a mixture of poor sales balanced with the keeping properties of the solution. (Legal note; this may be wrong!) If so, why don't Harman sell it in powder form which will keep well on the shelves. It could also be sold cheaper perhaps? As Michael Maunder of Speedibrews says, 'we don't sell water.' Just a thought.