Very good response Forkdave,
I would like to add the following:
A number of years ago I worked for a major forklift supplier and was supplied with the following information:
Electric VS LPG Forklift
Total operating costs over 15 year lifespan of each forklift type including purchase price, maintenance costs, repair costs, Fuel costs, electricity costs, battery replacement costs, and trade-in value at end of 15 years.

LPG Forklift: $2.38 per hour
Electric Forklift: $0.85 per hour

And this was before the introduction of AC Electric Drive systems which are reported to be 31% more efficient than DC Electric Drive systems.

I have driven the newest 5000lb pneumatic AC Electric forklift and was astonished at the power on acceleration and lifting speed, easily matching a 52 Hp pneumatic LPG forklift.

The downside of Electric forklifts is the initial purchase price is higher because of battery and charger costs are in addition to base forklift price.
The downside of pneumatic forklifts is the shorter overall lifespan, 15 years to the boneyard VS 25 years for the average electric.