I was totally enthusiastic with my first Swytch Kit (ECO) in 2021. It delivered good pedal assist on climbs ... and still does to this day! However, a strange thing happened twice in my case: after 6 months of use the electrical components in the handlebar mounting bracket suddenly failed to deliver power to the motor. The support from Swytch was fairly good, and after two months of troubleshooting they finally came around to replacing the bracket. Then it happened again about another 6 months later (Aug 2023)! Though out of production, they did provide me with another ECO handlebar bracket which is working still (Oct. 2024). In the meantime, I had ordered an AIR upgrade kit in 2022. When it finally arrived in June 2023, the boxed parts were just bobbling around loose in the larger shipment box and no documentation at all was sent - not even a packing slip. The ordered A-Frame bracket was also not included and Swytch and after 6 months of getting the runaround from various Swytch Support contacts, the offered to send me a sattle mount instead. I accepted and have this mounted in parallel with my ECO kit. AIR was/is a big disappointment when it comes to power delivery and compared to ECO actually was a downgrade in this regard. AIR is good enough on straightaways and moderate climbs, but it can't handle long or steep hills like ECO. I totally agree with the review from Larry Gross [https://www.reviews.io/company-review/store/www-swytchbike-com/23425189] regarding backward compatibility and long-term availability of parts (batteries and mounts), which is why I hesitate to buy another Swytch Kit. Plus, the price just for an upgrade to MAX has gotten outrageous: the last offer of 60% off of MAX sounds great, but you do the math and realize the normal price would 1000 Euros! YIKES!