Good suggestions from other folks here. Remember that extract is most likely going to be less fermentable than an all grain brew due to the lack of free amino nitrogen and also the possible addition of crystal malt to the original mash (you really have no idea what is in those extracts.)
I'd get away from LME completely as it tends to not be as fresh as DME, or, to be more exact, suffers more from oxidation. And as others have said, subbing a small amount of sugar will help dry the beer out.
On top of everything you might be surprised how easy all grain brewing is, and if you are making 10 gallon batches you might already have the most expensive parts: The boil kettle and the chiller. Do a search fro "Denny Brew" to find Denny Conn's quick, cheap and easy batch sparge method. It's what I use and it makes great beer.