What is your definition of "OK" ? What kind of criteria would make something "worth it" to you? Are you particularly tall or perhaps a bit hefty? For taller people, exit row seats may be ideal but for those on the "big" size in other
Refurb vs non-refurb isn't really an issue since you're flying in September when you can assume almost all flights will be refurb'd. The refurbish doesn't affect the rear section of the main deck economy cabin, but it does mean the installation of newer PE seats, which have received mixed reviews. Though I don't think the differences (at least on the A380) are enough to avoid choosing PE if you would have chosen it on the non-refurb.
If you are flying QF8, you should note that there are always lots of free economy seats due to the payload limitations of that flight. If you have gold or platinum status, you may be able to get a "comfort row" where the whole row is blocked out for you. This is much more worth it to me compared to an exit row seat with an immovable armest. This only applies specifically to QF8 and not QF7 or other A380 flights.
My strategy recently on flying to the US has been to choose PE for QF7 and economy for QF8. For QF8, a comfort row or at least a spare seat beside me, is quite likely, but not guaranteed.