Hi yserius,
The Dorelan Delice appears to be 100% natural latex … probably Dunlop … which is a good quality material. It also has 9 zones (which are probably overkill) but if the zones are “right” for your body they may help with alignment.
The Pirelli PS16 also appears to use 100% natural latex (also probably Dunlop) and has 7 zones which is a little more reasonable but also probably overkill depending on how well you “fit” the zones.
In terms of materials they appear to be very similar and the Delice has 1 cm more latex than the Pirelli so they would be very comparable in terms of the quality of the materials. Of course you would still need to test each one to see which is most suitable in terms of PPP (Posture and alignment, Pressure relief, and Personal preferences) because they are probably different in terms of the softness/firmness of the layers inside each of the mattress.
You can read a little more about soft solid gels such as Technogel in post #4 here and there is more about gel materials in general in post #2 here. A forum search on Technogel (you can just click this) will bring up more information about it as well.
Phoenix