While surfing web for references I found that there are roughly two types of gamers: those who like post fx and those who don’t. Personally I like them where they can emphasize the effect in some situations, but not everywhere ofc.
Yep, I’m planning to go Marketplace once it’s done. I also have couple of other ideas for more screen after one is finished.
I’ve been working hard towards dynamic droplet simulation, watched tons of rain videos on youtube 
Below is the first result. Don’t laugh too hard though 
Turned out it’s very difficult to fake animated droplets and making it physically correct will involve fluid simulation (which is too much for a screen effect).
I will continue tuning the algorithm and will add small static droplets as well in the future.
Surfing the forum and docs I found that distributing code is not allowed on marketplace at the moment and dynamic droplets simply aren’t possible in blueprints (mostly due to bad rendering to texture support). So I guess I have to drop at the moment until marketplace allows cpp 
How come you need to add C++ to get effect working? You shouldn’t need anything more than a Material/MaterialFuctions to implement a system like (a blueprint might help, but it’s not necessary).
I was also looking for ways to make the water stream down the users camera view, using masks, gradients, Panners and normal maps should work in case. I also have one that I will be adding to my community project soon so that when the player goes from underwater to above water, I get some streams of flowing water (and water droplets) that occur for a a few seconds before fading out.
If you absolutely need it, then add a tutorial to show your end users how to set it up should work! 
No-no, dynamic drops aren’t solid textures in my case, on the video above the texture is generated at run-time. I’ve seen a lot of those lately, read many papers and if you want good looking rainy effect you need to actually generate droplet objects and simulate them (there are several ways to do it).
By panning textures you can’t achieve the behavior of the real drops (although a sprite sheet will probably look better but even in case there’s no interaction between the objects). I have panning since day 1, if you look at the very first video there is distortion effect which is done with the same material and it uses uv shifting, but its capabilities are limited.