I have 250ml and 500ml but it would make sense to only have 8oz-250ml and 32oz-1litres as it caters for both the enthusiast and pro. Zephir and Keramik are the best 1-2 twins or combos since sliced bread.
You can decant the 1litre into the 250ml for on the job operation. The Rupes bottles look like they built to last a lifetime and to keep things professional decant Zephir into a smaller Zephir bottle and same for Keramik. Just keep the litre bottles for storage at home and the 250ml's as on the go. I do the same with Menzerna but their labeling is cheap and peels so gotta remember what I put in there.
Yep... 500ml proved to be an unpopular size and was discontinued. We have the 250ml and 1 liter and with the launch of the nano 150ml, which is perfect if you only need a small amount.