I love these ideas! The strobe could easily also be a tachometer by adding a speed "readout" by flashing the hertz out when you hold the button down for 2 seconds.
As an embedded engineer, I realize that all these features add code space, so they all may not be implementable. It would help to code them in assembly rather than C if codespace gets tight. On small embedded devices, I always use direct assembly for this reason.
But I digress....
I love the features of my Arc4+, and I love more features even if I don't directly have a need for them. But the biggest hurdle is adding all this stuff with a one-button interface. If I was designing a light based on what I have learned about the Arc4+, and what I know about UI (User Interface) design, I would try to enhance the basic user control hardware. (right now this is only a rather poor single stage push-button) This way the multitude of features would be much more valuable and easier to use and implement.
I know it may be difficult, but it would make the light MUCH easier if maybe a rotary encoder could be added. Like say the head was not threaded and instead assembled with a bushing and an internal snap-ring such that it could rotate infinitely without unscrewing. Add a spring detent and some sort of encoder, either optical or electromechanical and now you have a "knob" that turns. (the lower half of the body)
I thought of this after watching several friends try to twist the head, mag-lite style when I handed it to them and said it has multiple brightness levels.
The knob could have 16 nice snappy detents in it for the brightness levels. (15 levels + one "zero" level for button lockout) In default mode, you click on, click off, or hold for momentary, just as it is now, then rotate the cap to choose the desired brightness. Beautiful, simple, intuitive. For more advanced operations to please the gadget freak (me), the 16 position encoder would be great for selecting flash rate for the Strobe (tach), selecting menu options, etc.
But the basic ability to just pick it up and use it by anyone would be assured. Just engrave a label above the knob to indicate it is rotatable and label it something like this "<- INTENSITY ->". I'm not a mechanical engineer, but I have sketched a drawing of how this could be made, similar in dimensions and assembly to the 4+.
The other, less useful option could be to add a multi-stage button to the design, much like many digital cameras use. A gentle click, and when pressed harder, a second click. Both would have to have good tactile feedback and not be "spongy" or quiet.
I recently tore my 4+ apart after plenty of button frustration and constructed a recessed button and improved the tactile feel. I am quite happy with it, and I can revert at any time to "factory" if it needs service, or I get tired of it. I will post the details later in a separate thread.
-Phil