IMAX and 70mm are technically the same thing. IMAX is just 70mm film run horizontally instead of vertically, which gives it a larger frame.
And I agree that digital looks lifeless compared to film. I don't care that most films go through a 4K DI before being printed back to film, I still want to see it on film. I've yet to see a digital projection that didn't leave me feeling cold after it was over.