It has confused me for a long time.

After I installed EC, I always got error alerts such as 10417.
I heard others said clients who get declined by EC could get the payment through by retrying with paypal standard.

So I am wondering if I should use EC or standard.

Do you really notice that EC does increase conversion rate?
I am using bother EC and standard now on my site. And asking people who have trouble with EC to try standard checkout.
And according to my order records, there are 50% using paypal standard instead of EC.

I think it's confusing to have both EC and standard payment options on site. So I am thinking of remove one of them.
The question is which one should be removed?