Personally I chose a new over a used Model Y this year because the Juniper release includes a new front bumper camera which could prove crucial in certain unlikely scenarios, and improve overall self-driving. It’s important enough that there are rumors they’ll offer the option of retrofitting it onto earlier versions: https://evannex.com/blogs/news/how-to-identify-your-model-y-...

Also HW4 likely unlocks significant self-driving performance that the earlier hardware stack cannot accommodate, and will support features that are yet to be released for a longer period of time.

Which is all to say: looks to me that the progress is significant.