that pole you're looking at is almost exactly what I'm using, except I got mine at Best Buy and it's branded DigiPower
http://www.bestbuy.ca/en-CA/product/...501680956een02
it's great because it's very collapsible for travel. I also have the GoPole but don't actually like it, it doesn't allow as much freedom of positions near the mount. The only thing bad that has happened with it is that the lanyard cord ripped fairly easily, so I jerry rigged a keychain hoop with a dive flashlight lanyard and it's been fine ever since.
I don't use red filters shallower than 20 feet. For diving, I use the BackScatter Flip 3.1 combo (recommended by a fellow Canreefer). I had it imported from California total cost about $150 plus about $15 in duty.
http://www.backscatter.com/sku/bs-flip31-combo.lasso
However, food for thought, I hear Aqua Sport Scuba in Marda Loop has become a Go Pro dealer, not sure what they may have but could be worth a visit.
Have fun with your Hero 4, I'm just using a Hero 3+ Black