I am sorry, but this topic is not related to kobra 2 neo or klipper firmware, it is a poll about klipper host hardware. But, answering your question, it’s not really that big of a diffrence between the outdated firmware and latest. You can continue using older build and you’ll not lose much. If you really want to compile it yourself you could use 36KB bootloader offset, PA2 and PA3 (usart2) for communications and either 8Mhz or 12 Mhz external clock source. I think this should help.