That bug report isn't about data being corrupted due to mixing hardware with different queue sizes. The problem described in that bug is that if you add a device at runtime with a smaller queue size, the queue size of the mdraid device correctly decreases. However, if you have a dm-crypt volume mounted on top of that when you add the device then dm-crypt doesn't have any way of detecting the queue size change and stuff breaks. Just mixing different queue sizes shouldn't cause this, and neither should adding devices to a mdraid volume without anything stacked between it and the filesystem.