The difference between the saka and velox is that the saka is just a doubled bungee, while the velox has a tiny purpose made block at the bottom that the bungee bends around. Maximizing the amount of stretch you get from the bungee.
I keep my haas attached to my chest harness, then bring the tail of it around the left side of my torso, behind my back, and clip it somewhere on my right hip. The one time I left it dangling from my hip recently, I snagged the micro biner on the bungee in a swing and snapped the bungee. I was heart broken, but then replaced the bungee and moved on.
And someone else mentioned this earlier so I will throw it out... I use the haas in the tree all the time, even for relatively short ascents. Especially now with the clip in style, it is easy as pie to reattach. The attached foot loop design was always a bit cumbersome for me personally. I made a footloop that I leave on my boot. Soon I am gonna make a second and just leave each on the two pairs of boots I wear, permanently.