Quarq or P2M on Cannondale Si crankset

[nagge]

I've got a Supersix Evo with a Hollowgram Si crankset, what would you suggest as far as crank based power meters go?
Ge a Quarq Carbon BB30 or a P2M eco spindle for the current cranks? I would use Praxis works chainrings in both scenarios.
My calculations show that the P2M/Hollowgram setup should be about 50grams lighter and a bit cheaper as well.
Any pros/cons with either solution?

[glander]

Get the Quarq it will work properly everytime.

[gwilson]

I think the price of the P2M NGeco is pretty hard to beat for a spider, but if you are fine with a left side power meter, stages makes an Si left hand crank power meter for a bit cheaper. It will also be lighter than any spider options by far

[dudemanppl]

P2M > any other option listed here.