The conservation of momentum isn’t violated just because the mass dispersed is too small to measure. If a miniscule even microscopic mass is dispersed at speeds approaching C, a great amount of momentum can still be maintained. The issue to me would seem controlled vectoring of such a device.
Its also only violating conservation of momentum if one throws out Quantum Physics and virtual particles.
The tests regarding the Casimir Effect have indicated their existence.
This would be applying the Casimir Effect on a continuous timeframe.
Of course! Er...I think maybe...
A set of these devices could be mounted on gimbals and powered up and down and vectored to provide thrust in whatever direction and at whatever power levels was wanted. And since the EM Drive does not use any reaction mass, there is no exhaust and they can be mounted internally. With enough power, an EM Drive craft could even hover and move about noiselessly.