Fluid Flux v Water System for Rivers & Lakes

As the title suggests, I am looking for some feedback from users who have used Fluid Flux in the past.

I know it is GREAT for coastlines. I really like the looks of it and it is relatively easy to set up/use. However, I am having trouble using the fluid simulator for rivers and lakes on a landscape. I can use the simulator to fill a particular level with water but am having a heck of a time getting the underwater processing to work. In the ocean, the underwater looks and sounds great. I’d like to replicate this in lakes.

That being said, I am wondering if anyone who HAS used FF and the built-in water system of 5.4 has an opinion on which program is better, in their opinion, for lakes and rivers. In Australia FF costs about $800+ so I want to make REALLY certain it will do what I need it to do before making the actual purchase.

I’ve asked on other forums and have even spoken to the developer himself, but haven’t gotten a solid answer yet.

Help me, Unreal Community; you’re my only hope!