Another vote for the buildcraft filler. The clear pattern (9 blocks of glass) is your best option.
I use it. The more power you give it the quicker it runs.
Another vote for the filler. I use it a lot to repair the 'damage' my quarries do. You can either have it clear an area or you can have it fill areas. I use the latter to build a 'floor' over the hole my quarries created.
Filler works great, but honestly, if its dirt your clearing, the IC2 laser is wicked fast! I've used this method a few times and it really can't be beat.