One helpful point is that the firmware for the n1 is the same, it simply enables new features related to the I/O ports. This means a user could swap in a new controller with no impact to their system. Maintaining firmware compatibility was just one of the challenges [Josh] faced along the way. Squeezing additional functionality into the small number of user-exposed I/O pins was a chore, but dealing with supply chain issues was a big headache:
…make a revision that leveraged the parts I had, along with ensuring that the parts I needed were achievable to purchase in a reasonable time frame. Some parts orders for this batch were placed nearly a year ago.
Check out moteus if you need a brushless servo controller. We covered the previous major upgrade last year, which was primarily firmware and interface focused.