They do weigh less, but not a whole bunch. Something on the order of maybe 20-30 grams, tops, for the piston I was looking to have made up. Oil squirters most definately will help, but isn't a sole solution to the fact that they expand more since they get hotter. As far as oiling, we've been putting forced dual pin oilers that are machined into the piston by JE to further aide with lubrication. JE's forging on the other hand takes a twist to how they increase the strength (since it runs hotter and they tend to be used in high rpm/horsepower engines. See the attached picture for comparison vs a standard slipper skirt piston from JE:
