I don't think this would slow you down though, you would have less power at the top and bottom then you would at the down stroke, so you could have a better. Like those elliptical rings that Bobby Julich is using.
Not bad but not quite there yet.....
Let's forget the crankarm for a minute and focus on the leg of the rider; due to increased stackheight his lower leg has seen an increase in length by about an inch with respect to the distance sole/center of pedal axis.
This means that the femur muscle now has to stretch further.
The pivotal points have been shifted noticeably: ankle to knee is still the same but the ankle is now at stackheight distance from the pivotal point of the pedal.
As we can see the stackheigt introduces a shift in the lever/pivot series that inevitably introduces a loss in energy transfer.
While you can train yourself to ride that it certainly isn't the most efficient.
Worst case scenario: you'll be shifting up one gear to be able to spin the crankarm system around.
Anyone who knows the ratios of gearing systems knows this isn't the right way to gain effeciency while pedaling as the same amount of energy now goes to a lower gear.