Just a note - I understand Opus isn't the be all and end all of ICC aware image viewers/processors, but one thing it really shouldn't do is drop the profile when converting from, say, TIFF to JPG - even if it's not really aware of profiles for display etc., it should at least tag the output file with the same profile.
Would make the convert functionality a LOT more useful.
I don't think any metadata is preserved when converting between image formats at the moment; only when altering images without changing their formats.
If you need more advanced conversion functionality but want to remain within Opus for convenience, ImageMagick is a good, free tool with a conversion tool which can be integrated into Opus toolbars, hotkeys, etc.
I can't think of a pre-made toolbar, but ImageMagick can do so many different things that you'd probably end up changing it anyway, unless what you want happened to be the same as the toolbar creator.
ImageMagick's command line is really easy to use with Opus, though. Here's an example Opus function which will use ImageMagick to convert from any existing format into JPG format:
This works a treat - any way to track it's progress though? With large files it's totally silent till the output appears which is disconcerting...but I am guessing there is no way to do a progress bar or similar??