Nice result. The 'gritty' look of the lower layers will be due to small steam/decomposition bubbles. If you dry your PETG you will see less of that.

If you have no problems with the lowest temp (and the layer bonding is still OK), try going even lower. I can easily print down to 200-210 C with my FF. Disregard what anyone advises and do yourown tests. I invariably find that the temperature recommendations are too high.

What you want is no edge curling and nice flat bridging over the hollow spaces, and still good layer bonding. A break test(pliers may be needed) can help you with the latter.

Temperature will also depend on printing speed, at higher speeds you will need a higher temp in order to melt the plastic.