A few years ago I used to be into vintage camera collecting and repair. Now that I'm interested on vintage watches I would like to learn how to service them.

I'm looking at several generic timegraphers. There are model 1000 (4 buttons), 1900 (larger screen), 2000 (way more buttons), 3000 (more expensive than the 2000) and 5000 models (different button configuration, even more expensive). They seem to be rebadged by several vendors but all seem to be coming from the same factory in China.

Is there a website that outlines the different capabilities of these units? I'm trying to find out what is there to be gained by paying more for (what I hope would be) the more capable machines.