it will be a good buy opportunity!
Yup.
The thing I can't figure out though, is whether Gox is more likely to bounce off, bringing Bitstamp with it, or will gox climb to about $220, while bitstamp hits $200, and then the Bitstamp, having the wedge, falls, bringing Gox with it, and then Gox's $200 proceeds to act as a support, actually ending the $20 slide.
If its the latter, this is still a fairly good buying opportunity (right now.) If its the former, you'll likely be able to buy at $150-$160 again in the near future on Bitstamp, so no need to get too worried.