Plus, I can't remember installing OOO taking over half an hour. I'd be surprised if it took 10 minutes...
That depends a lot on the rig - in my case, with an ancient AMD Athlon 64 3500+, I'm pretty sure it would take a long time - although I've never tested it with OOO, but with some other large archives.
Also, not really necessary to repackage for BAIN as said. Keeping track on a couple of optional esp's that are manually installed should be rather simple. In my case I'm not using any OOO optionals so I gain nothing by repacking it.