Erasing with one finger is an idea with potential, but everything else on my phone uses one finger for panning -so I'm never going to learn it. So here's my idea:
1. One finger pans.
2. Double tap with one finger and it goes into erase mode. Some feedback should be given that this has happened.
3. Now one finger erases.
4. But, THIS IS KEY, as soon as your finger is lifted, then it goes back to one finger pan mode.