I would guess that the essential electronics of all these shake lights are the same. After the charging phase, the LED is powered by the same type of 1F 5.5V capacitor. So once the capacitor is charged up, there should be very little difference in performance.
The main questions are build quality, switch quality and ease of use (ie the shaking process). The main use of this light is as an emergency light that you can store practically anywhere for however long it may be, without having to worry about the battery condition or charge. Once the emergency strikes, and you really need light, then just pull it out and start shaking.
With that in mind, one then can understand the need for a good quality build that uses plastics highly resistant to degradation, either through chemical contact or UV reaction. All wires must be properly attached as a break will render the light useless (a very scary thought in an emergency). The switch must also be as robust. The majority of pushbutton switches and slide switches are not protected and can oxidise while in storage, leaving you a torch that is next to useless (you can still use it as a baton
)
BTW, the switch in the Excalibur may actually be a slide switch as you can notice a very slight bit of space just behind the button.
I wonder how big the microforeverlight really is. Stupid webpage doesn't say. That's important not just for storage or carry options, but also because of the distance that the oscillating magnet has to travel, which then translates in to how fast one needs to shake the light (frequency). If the required optimal frequency goes too high because the light is too short and the magnet has to change direction of travel too quickly, then it becomes very hard to use.
There are, I believe, quite a number of us flashoholics who have created an almost similar emergency flashlight from that Russian handcrank light. It was a good concept, with a handcranked generator provided power to a PR-bulb, but you had to keep cranking or there would be no light.
So we went one better and replaced the bulb with an LED and put in a couple of memory capacitors, 0.5F 5.5V or 1F 5.5V depending on what we could find. Same result as the shakelight in that some 30-seconds of cranking gave us similar amounts of light for approx. 5min.
What we lacked was the focusing lens found on the shakelight, which serves to collimate the light in to one seriously bright spot. What we gained was that the magnets used in the Russian handcrank light wasn't as strong as those in the shakelight, so we didn't get as many steel objects stuck to out light and didn't erase tapes and diskettes or mess up CRT units like TVs and monitors. The handcrank also meant that as the light dimmed, we could keep it going with occasional cranks of the handle while keeping it trained on where we want the light to shine.
I, myself, keep one shakelight and one handcranked light in my car, where the heat would kill lithium batteries in a month and alkalines in a week. It is still not the best solution as the light is not very bright, but at least I don't have to replace batteries every month. And where the rechargeable batteries in my Everyready Dashlite (emergency light kept recharged in the cigerette lighter socket) has already kicked the bucket, my shakelight and handcranklight are still in perfect condition.