Change the filler to stop it's use as a mining tool:
1. It empties from the top down now.
2. It uses less "max power" now.
3. Entity items dropped by the filler last 20 ticks.

It still works very well (better in fact) as a clearing and building
tool, but it's not a mining tool any more.

With thanks to the Mindcrack crew for demonstrating it's obvious flaws.