Good summary Mark, I just have a few things to add.
it's not plug and play
I think you mean it's not hot-swappable. I have yet to see a modern encoder that is not Plug & Play (meaning the computer recognizes it as a keyboard without the need for additional drivers).
Actually, what you mean is it's not USB - in other words hot-swapping is not officially supported by the specification. Neither is the KB16, but I understand that you were trying to make a point for the keyboard pass-thru. Having said that, I hot-swap the KeyWiz all the time, and one of the best uses posted so far for the KB16 (individual encoders for swappable panels by Buddabing) would require hot-swapping of the KB16.
It is my understanding that that is how your board also works, except that your board only supports 16 inputs as compared to the 32 inputs supported by the Keywiz.
There are other differences - in order of importance to an arcade cabinet user:
32 useable inputs for the KeyWiz as opposed to 16 useable inputs for the KB16.
24 Shifted inputs for admin keys for the KeyWiz as opposed to 0 for the KB16. (And KeyWiz admin keys can be activated automatically with a single button using RandyT's adapters).
Keycodes can be loaded from software (stored codesets can be loaded from a batchfile prior to launch) for the KeyWiz as opposed to manual input from a keyboard prior to application launch for the KB16.
Two codesets (the default MAME compatible and one programmed one) are always loaded and available by pressing the Shazaam! key and moving the joystick left or right (unique to the KeyWiz).
I'm going to go out on a limb and say that I would expect direct input to a microprocessor line (KeyWiz) to perform better than multiplexed connections (KB16), but I suspect the KB16 is not noticeably slow in typical applications, and I have never seen a head-to-head test of any encoder on performance issues.
KB16 uses EEPROM, KeyWiz uses SDRAM but KeyWiz software can be used to load the last used keycode, creating a Virtual EEPROM mode.
Wiring is sortof a toss-up, but not a big deal either way. With the KeyWiz, you can run a single ground wire to all of your microswitches and back to the encoder. With the KB16, you either run individual grounds, or you run at least two separate ground wires to connect your microswitches. The practical implication of this is that I could hook a Perfect 360 or Druin interface to any input on a KeyWiz. On a KB16, I would have to carefully make sure that all the inputs were on the same ground bank. In reality, this is probably not a concern, as with 16 total inputs, it is usually not practical to do dual Perfect 360's, etc.
I haven't seen anyone attack your products here without first being provoked by one of your BS statements. Knock it off.
Well, in fairness, I probably have attacked the product without being provoked first by one of his statements, but that is because it stacks up so poorly. To summarize - these are the only situations where the KB16 excels over the KeyWiz Eco:
As mentioned above, the unit could be useful as a dedicated controller attached to removable panels. Here, EEPROM is the determining factor.
For a single player (or two player alternating) cabinet - the unit would be acceptable, if the price is lower than the KeyWiz, otherwise you could just use a KeyWiz and not utilize some of the features.
EEPROM is an advantage, but not in the ways most people think it is. If you hot-swap controls, SDRAM encoders will revert to default settings. In the case of the KeyWiz, this is the MAME-compatible keyset, and in MAME you can reassign keys to match ANY default keyset. So where this would really come into play would be if you principally used the encoder with PC games or older Emu's that didn't allow reassignment of keycodes AND you wanted to hot-swap the encoder. In this case, the KeyWiz will require you to activate it's software either from a desktop shortcut or a batch file prior to loading the game, and an EEPROM-based encoder will not require this. But I think that is a small minority of the users here.
To make this short and sweet: For the same price point, the KeyWiz ECO is basically the same unit as the KeyWiz Max (with the switchable pass-thru and screw terminals removed), and the KB16 is - for all practical purposes - very similar to a 16-input programmable keyboard hack.