I don't have any issues with aggressiveness with my albinos. They don't bother my betta, but they don't let him push them around either. When they're not scrounging around for food, they either sit on the bottom resting or skitter all over the tank. Like n25philly stated, they often crash into each other or sometimes crash into Gray since they don't seem to watch where they are swimming. Gray spooks a bit, then keeps on doing what ever he was doing.
Again, I often catch them "sharing" a wafer with my betta. Due to the betta's pig-ish nature, I often have to monitor how many wafers I drop and when it's time to clean up the scraps so that my betta doesn't get bloated.
I swear sometimes he steals the wafer from them just as a game. He only picks up the ones the cories are munching on. Once the cories leave it alone, he loses interest in it.
Here is one of my albinos. They do prefer a sand-like substrate, so I may upgrade to sand once money isn't so tight. It's not available in my area, so I'd have to either order it online or drive 2hrs to get it.
And just for fun, here's Gray stealing one of the wafers from the cories. He spat it out right after the picture.
They're poor quality due to my iPhone being zoomed in and already loaded with pictures lol...
Since I have gravel instead of sand, I use a gravel vacuum every week to suck up all the left over food that has fallen between the gravel that the cories cannot reach. With sand, it is easier for them to get a majority of the left over food. It's harder with gravel.