It happens to be a killer deal for me and I haven't promoted my unit or considered upgrading without that support. We were initially told that the first gen unit could be updated to add HomeKit support and that they were investigating it, when it turns out that it didn't have the necessary hardware support. I read the posts where it felt like it was pulling teeth to get an admission of that and it happened again with gen 2.
The interactions concerning HomeKit make me wary of further investment, even though they have a great product otherwise and it meets my needs. Apple's requirement wasn't about reaping licensing money, it was about product security and we've seen significant issues with Internet of Things devices falling prey to hacking and becoming instruments of mayhem. A software solution has been discovered and Apple is confident enough in it to replace the hardware option going forward. I would hope to see Rachio release an app update that brings HomeKit to the whole platform, rather than just be an gen 3 feature. That action would confirm for me the ethos of the company and I'd upgrade to a gen 3 when available and promote the hell out of their product with friends and family. For now I'll wait and see.