open source tracker shield

We are developing a shield to build a feature rich open source tracker, It will contain GSM, GPS, an I2C accelerometer, uSD card slot and a connector for a standard 3.7v LiPo battery with charge functionality.

All the components on the shield works at 3.3v so we were wondering if it make sense to design this shield for 3.3v only in order to reduce costs and power consumption, from the programming point of view it make no difference you have only to chose the right board definition in the arduino IDE.

PROS: lower cost (less components) lower power consumption (this is particularly important for a device meant to be powered from a battery) better match with modern sensors (if you want to add other functionality)

CONS: it will be only compatible with 3.3V arduino board. (I don't know if this is a real drawback, in fact an arduino PRO 3.3v costs about 20$)

What do you think about this?

Like this one?

function are similar, but we want to produce a shield instead of a full product, and we want to use an integrated gps/gsm module to further reduce the price.

I think you can reduce the user price by adding the ATmega328 and the crystal (<$5) to the board directly, instead of asking users to buy a 3V3 Arduino ($20+).