Hi again Matt,
Since it sounded so interesting i thought i would throw in a couple ideas to help make it better.
A couple other quick questions...
The AN851 is about a serial interface isnt it? That means an RS232 port for programming, which is ok with me for one, but it's not a USB connection. A USB connection would require on board USB to serial adapter or PIC internal program to do this, which i am not sure is possible yet. I havent explored this in depth though so i could be wrong here. As i also said though, serial is fine for me. If you could get it to work with USB directly that would be a big selling point i think because many of the Arduino products work directly from USB and people tend to like that because they all have USB ports.
Working from memory, the so called, "isolation resistors" are resistors that are installed right onto the main circuit board for many products. They have nothing to do with the post programming work function of the board. The only time they make a difference is when programming. They connect from the physical pin of the PIC chip to the real world, so anything that communicates with the chip after programing (using ICSP) has to cope with these resistors, but that usually isnt a problem. A secondary header which we might call the programming header would connect DIRECTLY to the required programming pins, so during programming the programer board would be able to take control of the PIC chip regardless of whatever else is connected to the chip for real world use. So say we had some sort of controller board using a PIC, the i/o pins would run to the external world (soldered directly for a permanent installation). The external world signals might run from 0 to +5v, but because of the isolation resistors the chip would never see any of those signals because there would be a resistor between the PIC pin and the real world, and the programmer board would be connected DIRECTLY to the PIC pins via the programming header.
Obviously this would not work for every signal application, but how hard is it to jumper out a few resistors (maybe another option).
Options are usually attractive to buyers because then they can envision lots of usage scenarios. Of course it is up to you which ones you want to implement and which ones that can exist based on pure documentation. Oh yeah, good documentation is nice too
Another option would of course be different part number PIC chips.
Since you can design boards then i would think you have lots of options for doing this kind of thing.
I guess i saw a future for something like this because i've always liked the PIC chips too and so the easier they are to use the better for me, and i would believe for others too then.
Yeah i guess the initial cost would be much higher than a typical Arduino board. What about the cost of barebones boards say with DIP chip package layouts? That's something that a lot of people can deal with.