I write this to seek your opinions and suggestions. I will divide it into two parts

1. Business

I was asked to convert a lab prototype for production runs, but with enhancements. The prototype was made using 89C2051 and C source is available. However, the enhancements require adc and pwm. My other constraints are

1. Space - PCB real estate is very small about 30mm dia circle.
2. Low power and low dropout - unit is portable and I will be using a li-ion battery (LIR3048)
3. Cost

I have short listed two

1. P89LPC935FHN - (Philips)
2. ATmega48V-10MU - (Atmel)

The customer has done a market survey and committing a 10K qty for pilot run and planning for a 100K ramp-up per year. With this in mind, I ask your inputs

1. How is the vendor support? how do you rate them?
2. What is the minimum sizable qty for the vendors to be interested? (not all customers are equal).
3. What are the issues I should consider at these quantities?
4. How do guys handle the programming part?

2. Technical

The short listed MCUs have their own advantages and disadvantages over the other, but non-critical except for one. I understand the LPC uses the Vdd for ADC ref (unless I missed something). Due to the constraints mentioned above, (although it is against the books) I was toying the idea of operating the MCU directly from the battery until the supply voltage drops to 3V. My concern is, since I will be using the ADC which is referenced to Vdd, there is a variation of 0.6V (ie., 3.6 - 3.0 ) on the Vdd. It is about 15%. Although the application can tolerate this, I would like to have some buffer. Is there a better way to do this?
I was thinking of using a ultra low power LDO regulators like LP3984. Any inputs?

regards,