Just did my first bigger edit only with JOSM. Before I was usually using potlatch because it is far easier to use for many simple tasks.
Wanting to take advantage of geo-referenced pictures, I ended up doing all the work in JOSM instead. Some differences make it a little tricky to switch from potlatch, but the presets and all the little helpers are very nice - once you know what they can do for you. Saves a lot of typing for sure. The validation before uploading is also quite nice.
I think except for smaller changes and tweaks I will stick with JOSM now.

One thing that annoyed me a bit while editing and correcting some stuff were the cases where multiple areas would share common nodes. For example a street with a parking next to it. Is there an easy way to resolve these problems and kind of split up the different objects using the same nodes?

Today I took a look at the area of Düren and tried to improve the map metadata quality a bit.
In my opinion there were many cases of "abuse" of the name-tag and I hope I'm not the only one seeing it like that because I would hate to screw up good data.
What I found were especially - but not only - meadows, farmland and so on that was (correctly) tagged with the landuse-tag and additionally someone used the name-tag to include basically the same information about the landuse.
To me it looks like the name was often used as a sort of comment. Other examples include the outline of a golf course or forest with names like "not ready yet" and so on. Of course it is nice to include as much useful information as possible in your map metadata, but I doubt that this way will help much as it is not very machine-readable. It should be far better to only use the predefined tags to encode this information. In a few cases I even found roads that were named "unknown" instead of leaving the name away and thus making them much easier to spot. In some cases I renamed the name-tag to a comment-tag to make clear that it is not really a name and to not falsely show it as one on the rendered maps. In other cases I just deleted the name-tag completely as it was redundant information in my opinion and should not appear in maps like that.

I would like to hear other opinions and experiences in these matters. so feel free to comment.