well, the 8mm leds in the smart string nodes have a wider angle of coverage, and the 5050's are more focused, i can see why they appear brighter.
as you build your stuff, this is where you take in account for what you're trying to do. if you need it to be seen from many angles, then the nodes are the way to go.
If you're using a flat surface that will only be viewed from the front, then maybe 5050's are the way to go.
Agreed. Maybe take a picture from every angle that can be seen where they will be and let that be your guide.