I actually believe the motion is solid, and there's a decent chance it will be granted, at least in part, and enough to delay trial past the election.
Truth is that the government spent more than two years digging into all this stuff, and building their case. So it isn't quite fair to stick Trump with a fast trial date especially given all the complications due to classified documents. And, the government appears to be continuing its investigation, and perhaps deliberately withholding the right to file additional charges. So given that the government itself isn't even done with this 2+ year investigation, how the hell can the defense fairly prepare at this point?