Difference between Express and Standard Replacement Service for iPad battery Can a user use Express Replacement Service to get a new battery if still under warranty? 

How's that different than Battery Replacement Service again under warranty?
With express service you'll get a replacement device before sending back your old one. That way you don't have to spend time without a device. 
It's available under warranty but will be charged. 

Price in Austria is 29€ incl. TAX to give you an idea.