One little thing I would like to see, and I don't know if this is really there and I'm just dumb. :-) I only collect roms released in the USA, so it would be nice to be able to see only the roms that are missing from my collection that are USA releases, as opposed to seeing every single rom that has been released. Otherwise, I'm definitely switching back to this.
I switched to Rominator for a while, until I had an issue with it resulting in the loss of all but 3 of my 450+ roms (and I don't think those 3 roms were actually the roms they were showing up as. *shrugs*) I'm currently in mid-argument with the developer because he believes that it was my "user-error" that caused the problem, whereas, I believe it's just his lack of ensuring that the DELETE command only deletes the SELECTED NDS files, and not the entire collection, regardless of what NDS files are selected. Beware the delete command. :-)