With the now available delta grade move-by-wires cyberware, they are now feasible for character builds, but they were missing a key feature. MBW3 and MBW4, by the book, are supposed to gain extra actions in the first one or two passes through an initiative turn. We can simulate that by adding 10/20 to their initiative roll, though this is mechanically weaker because the extra actions will occur at the end of an initiative turn instead of near the beginning.
These two address: https://discord.com/channels/564618629467996170/788953927269613608/1218251123249647756