I am using Refworks and exporting to Bibtex. I think moving to Mendeley will pay-off, but for me it means that all my references from previous work are expressed as Refwork ID#. Which means for me that I will need to go through the entire document and cross-reference them with the ID used by Mendeley (Author date).
I think maybe when I have time I will start this process as it does seem better than Refworks. However, the storage capacity (in Mendeley) is relatively small unless you 'super-size' and the account (at a cost). This means that I will not be able to export all 450 documents without paying for more storage.
Milo