Lance Hedrick did a lot of testing and found, to his tastes, starting with cold water gets a better result as it starts brewing at a cooler temp. In his testing he found the water that brews in a moka pot, when using freshly boiled water, starts extracting at a really high temp and more often than not will over extract. There’s a full video on it, it’s really interesting. I’ve played with both and didn’t find a noticeable enough difference to have a strong preference but I also just really like the style of coffee a moka pot makes in general so I’m not as picky.