I have not tried this one but mixed several other low contrast developers (POTA, Delagi 8) which need similar amounts (1-2 g/l) of Phenidone in solution. Common sources recommend using hot water to start, this is why Calgon + hot tap water is better than DI water which you need to heat separately. I was able to dissolve 50 g/l Phenidone in Propyleneglycol (or supposedly even better: Diethyleneglycol) and use this stock solution to put the required amount of Phenidone into cold water quickly. It's not cheap but worth the effort, and I don't use such a dev on a daily basis anyway.
For all those who care: low contrast devs give amazing results with night time exposures on Delta 3200 if they include strong highlights. The low contrast aspect of these devs compensates nicely for the usually high contrast of these scenes (which is even more increased by the Scharzschild effect) and thereby in combination creates beautiful and very realistic looking images that can be easily printed with grades 2-4.