The vented is very stable in both fade and turtle - fade is the same, the turtle on the vent is even more stable - you can hold it in a riser all day in decent wind. His vents do not suffer the same issues as some other makers vents (namely, his fly well and do not feel 'mushy') - he keeps the venting small.
The light vent is great in bumpy wind - it helps to smooth it out. I trick mine into the 20s with no concerns. The light tends to get faster and pull more as the wind hits the teens, so I switch to a standard or light vent at 12/13 or so.
I see the light vent as a replacement for both the light and standard, but there is much overlap. If you are the kind of person that likes to fly a fully powered up kite, then the light is super sweet in standard winds (I love it). If you want less speed and easier (less input speed) tricks, then the vented light will slow it down for you.
In any case, it's all good. I've got a full set and they all have the same feel to them, it's really a matter of fine-tuning to choose the right one for the exact wind, but they will all work well.
If you only had the SUL and vented light, you would be well off since you can fly in any reasonable wind with confidence. Then again, I could never part with my light and standard either!