Whilst I'm not a WP1 (only approximately 3000sc this year - all economy unfortunately), I too have moved over to Virgin for the next two months to see the other side.
I definitely prefer the Virgin 3A seating over the 4A. Also, in four flights, I've been lucky to have been upgraded twice! My last op-up with Qantas was in April this year (flying at least weekly). Service is like for like to me and don't rate one better than the other.
Lounge facilities are mixed. I prefer the Qantas menu/food options, however, Virgin wins on the choice of beers (Beez Neez) and soup. Apart from Melbourne, Virgin's lounge facilities appear to be a fair bit smaller than Qantas, especially considering that Gold/Plat's share the same lounge. Also, please allow patrons to take the odd newspaper/magazine on Virgin - stock up please! - Qantas doesn't mind people taking newspapers and magazines, Virgin should at least follow with newspapers!
Website facilities wise, I prefer Qantas at this stage, it may be familiarity, but I find the Qantas site more user friendly and a better look and feel.
Probably the most noticeable difference between the two carriers is the schedule. I notice Qantas frequency of flights are much better than Virgin's (it does become a great excuse to zip off from meetings on time rather than stay back).
So overall, Qantas probably hasn't lost me as a customer (even though the flight cancellations nearly did), but I'm more than happy to "test" Virgin for a few months before deciding on my preferred carrier.