1) I’m wondering what makes sense for a large collection of documents - is there a practical limit on the size/number of docs for an .ENL?
While there is a recommended limit of 50,000 references in an EndNote library (which conceivably would allow for one or more file attachments per reference), there doesn’t appear to be documentation concerning size/number for file attachments (e.g., Word docs, PDFs, etc.). However, presumably key limitations will be guided by: 1) the number of records (50,000 recommended), and 2) sufficient disk space on the computer. Also the larger the library, the longer it will take to sync to your EndNote online account.
2) Should I manage all of my documents with one .ENL master database, using groups to separate them by project and/or subject?
Working from one master library offers advantages such as: 1) maintaining all records and documents in one “location” which facilitates searching, retrieving, and managing/updating records; 2) lessening the likelihood of duplicate records; 3) ensuring continuity by “setting” the individual reference records’ ID number (as copying reference records between EndNote libraries changes the numbering sequence to follow that of the “receiving” library, so in-text citations/references in papers written using the “old” EndNote library will not be able to be generated using the “new” EndNote library).
The disadvantage of maintaining one master database includes: 1) slowed sync times to the EndNote online account; and 2) potential loss of the database due to corruption of one or more files, records, or the library file itself - but this is easily mitigated by maintaining ongoing updated backup copies (including an .xml file).
Having one master database enables parsing out records/references across multiple projects/subjects via EndNote’s “Group” function. However, the “Group” function is limited to 2-levels so you may need to develop a strategy for naming if you wish to incorporate subgroups. Refer to this thread for a workaround to create a faux hierarchy for subgroups:
http://community.thomsonreuters.com/t5/EndNote-How-To/Organizing-Group-Sets-and-Groups/td-p/24041
3) Any problems with using a Group Set containing projects, and Group Set containing subjects, etc., all pointing into one ENL data set?
One issue might be ease-of-use as the number of groups (maximum number of groups that is 5000) within the master library start to increase. So, as mentioned previously you may consider developing a strategy for naming/categorizing and tracking groups relevant to the project or the topic. Besides a naming strategy, you might also consider placement of the groups as they can be rearranged within the list.
4) If one master database makes sense, how can I merge several separate .ENL data sets?
You can merge separate libraries by: 1) copying references from one library into the other; 2) dragging and dropping references from one library into the next; and 3) importing references from one library to the other. Note that methods #1 and 2 (unlike method #3), does not automatically filter out duplicate records so you should run EndNote’s “Find Duplicates” function after copying/dragging-and-dropping in order to locate, review, and delete duplicated records. In contrast, method #3 of importing an EndNote library into another EndNote library enables filtering-out of duplicate records during the import process. (Refer to the online user guide for detailed info on merging libraries.)
One big caveat for merging libraries is that the records being merged into the receiving library will have their individual ID numbers changed to follow the numbering sequence of the receiving library. (EndNote uses a record’s ID number to generate in-text citations and corresponding entries in the bibliography.) Therefore, with the new numbering sequence it won’t be possible to update documents using the new library if they contain in-text citations and references from the “old”/pre-merged library. So you may consider maintaining copies of your old/pre-merged libraries in the event you may need to use prior documents.
5) What is the relationship between libraries and groups and share-ability? It looks like there may be some arbitrary restrictions on this. For example, I’d like to share a project group among several co-workers, with each person adding notes/meta-data which is merged into a master library.
For a quick overview of EndNote’s library sharing and syncing capabilities suggest you start at the EndNote website which has a page devoted to the topic and includes a short video: http://EndNote.com/product-details/library-sharing . As noted in the summary you can share the entire library (with references, PDFs, and annotations); everyone your sharing with can “add to, annotate and use the library – at the same time”; and there’s no charge for sharing or size limit.
Note that you can have multiple libraries on your desktop but can only sync one library to your EndNote online account. (You can subsequently elect to use a different library but will have to first reset your EndNote online account.) Although you can sync only one library to your EndNote online account (and share this library with designated co-researchers) you could also share different groups/subsets of references by using the Group function then sync the group(s) to your online account then invite your co-researchers to access the specified grouped library of references.
Refer to the Endnote training video “Sharing Groups of References”: https://www.youtube.com/watch?v=hSExPuxdbcM&index=18&list=PL7FCC6F78D0B80B91
and “EndNote Sync: EndNote X7.1 and Later”.
https://www.youtube.com/watch?v=YIzbdvRNz8Q
6) If there are any examples or publications on best-practices for this, would appreciate URLs, etc.
Don’t recall any publications or best-practices but understanding how the EndNote features work and may be doing a trial run may help. Detailed information is available in the PDF manual (which comes with the software), or more conveniently go to the Help section of the Endnote toolbar which links you to several resources (i.e., user’s guide, searchable knowledge base, training videos and live webinars, user community, etc).