I'm as obsessed with the Alexa look as just about anyone. I had a major shoot on Friday, I was toying with renting the Amira, as it is very affordable in my area. I don't have a lot of experience actually using it though, so ultimately, despite having plenty of budget available to rent a big boy camera, I decided to just shoot it on my tried-and-true S1. I didn't even use pro res raw, just regular 5.9k internal hevc. I monitor using the GHAlex LUT on my ninja v, so I can nail the look "in-camera" before I grade. I think it's pretty dang close. This screengrab has zero adjustments or color alterations besides just dropping on the lut.
If I can get 95% of the way there, and have higher resolution to boot, at the cost of maybe a stop or so of extreme highlight retention in certain situations, I think it really starts to be hard to justify, beyond just impressing clients and feeling super cool and hollywood.