I’m in the same boat, and they don’t expect to be able to ship until the end of May at the earliest. They do actually have the AR3 motor kits in stock, though. It looks like there wouldn’t be a loss of functionality if the AR3 kit/CUI encoders were used, though it would be a smidge more expensive ($40-50). The wiring is a little bit different and the CUI encoders need more than 3.3V. If I ran “AR4_teensy41_CUI_enc_sketch” to account for the encoder pulse differences, followed the wiring diagram of the AR3 (other than switching the limit switches to 3.3V) into the Teensy 4.1, and supplied the CUI encoders with 5V, would I need to do anything else?