I returned the revised editions of the Letters of John and James when they were launched as the pre-pub prices seemed steep for the level of revision - especially given my limited budget.
These 2 volumes are now $9.99 each in the Black Friday sale. I try to keep a tight rein on my expenditure, so I'd be interested to hear from those who've used and compared the revised editions with the originals to know if they feel the revisions offer anything substantially different.
I can see some reviews that lead me to believe the James volume may have more additional material than the Letters of John volume.