Well, the Lightstorms are noticeably brighter. They are probably the best built crank light I have ever used. They do suffer from the problem capacitors suffer from. Mainly they don't hold their charge for long. I am not exactly sure how long they are supposed to hold their charge. Mine goes from full brightness to completely dead in very little time. It is my understanding that this is not normal and should not be happening, but I don't use it often enough to really make a difference. My 3rd Gen Nightstars and then new jp's do not suffer from this problem nearly as bad. It takes a good period of time for them to drain. They are not as bright, but they are built very well. I would be highly surprised if any of them failed on me and are without a doubt the best shake lights ever made. Both the Nightstars and the Lightstorms will dim over their run duration. And by quite a bit. That's just the nature of the technology.
None of them are very bright by today's standards, but that's not really there purpose. They are supposed to be reliable and cost nothing to run. And they seem to do that very well. The Nightstar's are typically going to be more reliable simply because cranks have that chance of breaking.
