The shake lights are more a novelty than anything else. You simply can't get a high enough emf to generate without making the magnet/coil oversized. Something akin to swinging a baseball bat-sized tube.

On the other hand, the crank jobs have improved considerably. I started out with one of those Xenon bulbed 5 lb crank jobs, which was okay, but not what I wanted to be toting around inside a cave, just too darned big. Then I got one of those Grundig radio/lights with the crank. I found that replacing the akaline AAs was more convenient than cranking the gyro every 5-10 minutes.

Then I happened on a pair of crank handhelds at Costco that looked like the new model phaser guns from Star Trek-TNG. I decided to give them a try, and was impressed with how long the three primary LEDs ran on a 2 minute crank-up. The pair accompanied me to Baghdad, one by my bedside for those mad scrambles to the bunker, the other in my BOB. I used the one by my bed regularly, gave it a two minute crank once a week, and never had a problem. It got tossed around, stepped on, dropped in the toilet (clean water fortunately), and dropped on the deck often. It never broke, the case never cracked, it never failed to provide light, and if the charge was going away, I could give it ten quick cranks and have full light again for a couple minutes. That was the best $29.95 I've spent on lighting in quite a while. You won't get that kind of performance from a shaker. Three LEDs is enough light to get around inside a lave tube with, which is a demanding environment for adequate lighting.