g1smd - 11:48 pm on Aug 14, 2012 (gmt 0)
I'd be happy to lose 5% of my visitors if Gbot stopped banging my site 3 times for every possible page
...but they're not! as you said...
Googlebot last fetched the URLs 6 months (!) ago
Yep, so they aren't banging your site at all. And your real pages are ranking and so are some of the old versions of your pages via Supplemental Results for the IP, and the redirect gets the visitor to the right place.
I'd say you're getting an extra 5% added to your visitor totals, for no outlay at all. I'd not block it.