I would be more careful in your place praising the new Core-M chip. Have you tested it?
Nobody knows how will it perform. We will see on 10 April, 2015.
Core M has already been used now in Lenova's Yoga tablet and has a full review of it's performance on Anandtech (a well trusted site).
http://anandtech.com/show/9061/lenovo-yoga-3-pro-review
I will admit, I too had assumed performance would be more in line with the Atom brand CPU. the Core M seems to be impressing reviewers. While it is not i5 level performance, it should be no slouch.
Caveat: This assumes that Apple is using the same bin number as Lenovo and also not employing any additional throttling mechanisms to control heat.