When you smoke or vape THC, you control your own dose. You feel the effects immediately and you can just stop when you've had enough. If vape was, say, half as potent as smoke, you'd just vape twice as much. So potency is not as big an issue as you might think.
This is where edibles are more 'dangerous'--it's easy to eat too much because you don't feel it right away. Also, on the wrapper of that cookie or chocolate bar it says ('Contains 12 doses') in small type, in a place where you might not see it. An OD of THC can't hurt you, but it could be very frightening, especially if it's your first time.
A year or so ago, a buddy of mine gave me some concentrate he'd made. It was poorly made, and old too, and I didn't know how to use it. I found several companies now offer stuff to make vape juice out of concentrate, so I tried that. I found it VERY weak. I didn't get nearly as high as I do smoking it. No matter how much I smoked! But that's not the best example. You won't really know how it works for you until you try it. You can buy vape pens all filled and ready to go at your local dispensary.