Burt has a point.
If you switch to AVR you need a new programmer and about the same startup period you had with PIC's. Why?
You can stay with you current code for between $2 and $2.50 a chip.
If you are going to switch to C you can use the 8 pin PIC devices for about half the price. You can use the Junebug to program them and BootC to write the program.
My suggestion is that you focus. Sell a few units with the current design. If they are popular enough such that squeezing another $1 out of the design will be profitable you can do the redesign while the first rev is being sold.
AVR vrs PIC: People will always want you to use what they use. Not a huge surprise. From the top looking down it does not matter which chip is in the box as long as it works.
You are ready for production? Start selling the thing
If not dot you i's and cross the t's. Finish it.
3v0 (a software engineer)