My opinion regarding the matter is that a lighter piston (like an ultralight JE) will actually help the motor rev quicker to your 6800rpm shift point... if everything else is up to the task, that is (the valve train for example).
However, I cannot claim to be an experienced engine builder.... just sounds to me like your's is trying to save you a few bucks
Unless you are going to run ultralight rockers, titanium locks/retainers, alum. flywheel, undercut valves, lighter rods, etc. I don't see where it would be absolutely necessary.... I DO know that ultralight pistons are NOT to be used with heavy doses of nitrous.
Welcome back!