I also fly EC225s and wear Seregeti Drivers (non-polarised). I tried the gradient versions but found them to be not too good when sun was reflectiong off the water during offshore approaches due to the lightening of the lens towards the bottom. Great for driving but not so good for looking out hovering over water. The Drivers are perfect. No problem with seeing any of the screens or the radios with their LEDs.
I also have tried Silhouette sunglasses (polarised) and again no porblem with the screens, but did have problems seeing the radio frequencies as they were blanked out by the polarisation of the lenses as my head turned to look down.
I have found the Seregeti Drivers (non-gradient, non polarised) to be the best sunglasses for me for flying.