6.5.3 has killed MultibandCompressor, Overdrive and Q.
These were the old PPC plugs, but up till 6.5 they still loaded via the bridge - albeit temperamentally.
Now though you get a Syncrosoft error when you try and instantiate them. Others from that series such as Quadrafuzz and VST Dynamics still load fine.
I know these are old but for compatibilities sake it would be good if this was fixed in the next build.