Can you ask in a survey? – there are a couple other things you need to watch out for. Macs and the PC versions of MSWord 2003 and earlier have the old style toolbar and Word 2007/10 (and 13?) have the ribbon.
I wouldn’t go any further back than to X4 which has find full text and a simple group structure. Anything older the X4 I would not support (and after X7 comes out, neither will TR).
searching the internet for “what’s new” and Endnote brings up Queensland University webpage for certain versions and there are probably some others I didn’t investigate.