Vytas Marcilius, the Director of the LAK factory told me that the enhanced batteries with two additional cells per battery will be available to anyone who wants one. I intend to order them with Mini LAK # 29, which will be delivered to me sometime next Fall. While I was in Lithuania, I self launched a LAK 17B in 18 meter configuration, that had been experimentally upgraded to use the more powerful batteries. The launch was routine and powerful.
I think this signals the end of sustains in any LAK ship where the owner is willing to pay a little more for the powerful batteries. I understand they will be standard in the upcoming LAK 17C FES.