I now have the nitrile hose and the 100% rubber hose. The nitrile hose looks similar to the old type of rubber, but appears to be prone to kinking. If left in kinked position for a few days it does not want to unkink. Same goes for the 100% rubber hose. The nitrile product is a bit stiff for my liking, as is the 100% rubber. The nitrile might have the advantage of being resistant to heat and chemicals like petrol and oil. The 100% rubber would have limited resistance and would also be prone to perishing in a relatively short space of time. It is basically the same stuff that pencil erasers are made out of.

CONCLUSION: There can ultimately be only one winner and that is the black hydroponic hose. It looks good, feels good, you can bend it a fair bit without kinking, it is sag resistant, reasonably heat resistant and probably long lasting. For my money that is the replacement hose I would recommend. I am not sure if there are different kinds of rubber used to make hydroponic hoses. In case anyone is interested, this is the one I trialed specifically. https://www.ebay.com.au/itm/265274517759