My Johnny-5 project with Arduino and AdaBerries

Hey guys I got a few questions regarding a project I'm working on. I found one other thread related to this(http://forum.arduino.cc/index.php?topic=117199.0) but I appear to be further along in my project.

So I bought the Johnny5 robot kit from http://www.lynxmotion.com/c-103-johnny-5.aspx and my plan was to swap out the microcontroller and motor controller for a Arduino Mega and a motor sheild as a base setup, then add an array of sensors and sheilds to make an autonomous robot pet.

Here is a quick brake down of the base Johhny5 system (batteries not incuded in kit): 2 x 12 volt gear head motors 12 x servos 1 x SSC-32 microcontroller 1 x Sabertooth motor controller 1 x 12 volt battery (motors) 1 x 9 volt battery (servos) 1 x 6 volt battery (microcontroller)

Everything work according to plan...well almost. After ironing out some kinks I have managed to get Johhny rolling around as intended in a semi-autonomous manner. Animating the upper torso is pretty much straight forward servo control. After getting the basics under control naturally I though to myself "What next?" and off I went to my local parts dealer...This is what i bought for V1.5 :

Sensors: 2 x Ping sensor 2 x tilt sensors 1 x PIR sensor 4 x proximity sensors 2 x IR sensors 2 x force sensors (for hands)

Sheilds: GPS - https://www.sparkfun.com/products/10709 MicroSD - https://www.sparkfun.com/products/9899 VoiceBox - https://www.sparkfun.com/products/10782 EasyVR - https://www.sparkfun.com/products/10963 16-ch Servo - http://www.adafruit.com/products/1411

So my question is in regards to unforseen problems that could arise from stacking multiple sheilds. I'm going with the manufacturers recommendations for power supply. Any imput would be greatly apprectated.

Thanks