Ann: Xingyun Lake Application Video, page-5

I would imagine that the bulk of the larger lakes would have a fairly low water flow velocity considering the widths of the lakes involved. The videos didn't show any significant drift of product.
Wind shouldn't be too much of an issue if the product sinks below surface reasonably quickly which it appears to do.
Remember that most of the lakes are quite shallow so the product should reach the bottom quite close to where it is applied. Lake Xingyun has an ave depth of 5.3ms. Many of the larger lakes average around 4ms depth and less. GPS should make it very easy to track where product has been applied.
Sheer amount of product needed - I would see that as a positive, not a problem. I can't see why that would be an issue. More product, use more boats.
Regrowth just means more maintenance but Phoslock is reported to effectively cap the sediment surface, preventing phosphorous from sediment getting back into the water. Regrowth should only be a problem from fresh inflows. Fresh inflows, more maintenance.
I'm sure they will modify application techniques as required and as they learn along the way. I can't envisage problems that can't be reasonably easily addressed.
Those are my thoughts.
I did see a slight negative in today's news. I had previously assumed application rates of 3,500tpa for this lake but it looks like I need to revise that to 3,000tpa. Not a big deal on its own but my assumptions for other lakes are based on the rate for this lake and adjusted for volume differences.