Cold Plates versus direct expansion evaporator plates

As mentioned in previous posts the days of holding plate refrigeration are numbered and have been for many years.  In certain circumstances they may well be of benefit if they are TRUE EUTECHTIC plates....Most off the shelf self install systems using holding plates are really just "cold storage plates" and occupy precious box space that could be occupied by frozen product that truly benefits in energy terms taking into account LATENT HEAT OF FUSION. The reason for this is that unlike a true hold over plate they are filled with a mixture of propylene glycol and water and this mixture will determine the plate temperature to be a 0 deg F plate or a 20 deg F plate.. There is no physical conversion from liquid to solid, rather liquid to slop or slush at best, it it were a TRUE EUTECHTEC solution then the freeze of the solution and it's expansion would blow the plate. Therefore their advantage is not justified as they do not 100% achieve the thermodynamic heat laws governing  LATENT HEAT OF FUSION.