Can I use “uses-feature” instead of “uses-permissi

Question

In my app's AndroidManifest.xml I currently have

<uses-permission android:name="com.android.vending.BILLING" /> 

Is it possible to replace it with:

<uses-feature android:name="com.android.vending.BILLING" android:required="false" />

?

I'm assuming that as a result my app would appear in both countries with payments support and in those without. In the latter, in-app purchases would simply not work.

When uploading the APK with said modifications, Google Play warns:

"You uploaded an APK that does not have BILLING permission, or has a BILLING permission that is limited to specific sdk versions. BILLING permission is required for selling in-app products."

Should I ignore it, and still assume that purchases will be available in supported markets?