Hosting gear manuals might be useful (I don't like the way the sites that specialize in that want your contact details, or add their own watermarks to the files), but is there a copyright issue with hosting them?
My main request for improvement would be to do something about the crazy number of duplicates. Every time I start looking at the gear for a manufacturer I'm interested in, there are loads of duplicates. The form for reporting duplicates isn't great either. It would be helpful if it showed a preview of the item after you enter the URL, so you can see you've got the right URLs, and not entered them the wrong way around (i.e. requested to keep the bad one and delete the good one). Using multiple browser tabs to check the URLs is awkward on a phone.
I think a better "are you sure this isn't a duplicate? Stop entering duplicates, you clowns" check when submitting new gear would help too. Try to prevent dupes in the first place, so there aren't so many to report and merge later.
Finally, I'm not sure what the process is for "Needs Improvement" items when the item is incorrect. It doesn't seem possible for the submitter to change a bad item after it's been reviewed. So what's the point of reviewing it as needing improvement? Should it just be marked "completely incorrect"? And what happens to incorrect items, do mods delete them?
I want to help improve the quality of the data, but it sometimes seems pointless to review things if mistakes can't be corrected.
Edit: for example, I reviewed this to point out the gear was completely wrong (same manufacturer, totally different unit) and now it's a submission for the Analog Four that says "Machinedrum, no Analog Four here". Edit2: oh maybe only the original submitter can change the item? I've just realised that the user who updated the description on that item isn't the original submitter.