Can I stack two ND 1.5 instead of one Screw-on ND 3.0? Will I get the same result?

I am thinking of buying two 4x4 Schneider ND 1.5 then stack them instead of one Circular screw on ND 3.0, eventhough I heard how great the screw on B+W ND 3.0, but I like the idea of dropping in instead of screw on everytime after composing.

Would you mind to share your thoughts or even better if you have any pictures to show that stacking up will get the same result?

I have the Hitech 4x4 Prostop 10 stop and I hate it... didn't like the color cast..

Adding two more surfaces for light to bounce off of might promote flare. And would the extra thickness of the filter holder work with your wide angle lens when it's stopped down?