The 75i I have will not hold its last settings after shutdown. I bought a BreatheSmart Classic over 3 years ago and always keep it set to auto. It has worked flawlessly. When I turn on the 75i, the auto is never set and I have to manually set it each time. That's a small glitch, but its annoying. I also have a 45i and auto setting does stay set on with that. My other concern with 75i is that on auto it stays on Blue 99.99% of the time, while the BreatheSmart Classic seems the change when it should. I did call customer support (which is always excellent and very concerned & responsive) and was told it's because of the new technology in the (i) series which is more advanced. So to sum up: I've really liked Alen air purifiers in the past and highly recommended them. But for me the verdict is still out on the new 75i.