the bullets are expensive 500$ each last i heard for each 25mm shell.
should the xm307 live up to expectations, then it will be a rapid fire air burst gun, it should be able to replace the 50 cal (12.7mm) in infrantry suppression.
still for a military that equals the rest of the world in spending, this development feels kind of slow in my opionon, the USA should at least had the future force soldier up and running by now.