One thing I like about potlatch (the other is its seamless editing) is the ‘remember ways’ feature. It saves a lot of time when tracing road from bing images for residential areas. Is this feature incorporated into JOSM? I thought I read about it somewhere but countless search has found nothing.
I’m not very familiar with the features of Potlatch - do you mean Potlatch’s ability to apply a group of tags to a new way?
If so, the feature that comes closest to this is the “Paste tags” feature. When you have copied a way or node to the clipboard with Ctrl+C, you can then paste its tags to the currently selected way by pressing Ctrl+Shift+V
Alternatively, you can use the search box (Ctrl+F). For example, you can first draw several ways without tagging them, then search for something like “untagged type:way modified”, and then simply copy or add tags to all of them at once.