I think its a good question, but more importantly how do the specs of the GBA and the GP32 compare natively? 
GAMEPARK (GP32)
Display 3.5" Reflective TFT LCD(65,536 concurrent colors) 
Resolution 320 X 240 pixel 
CPU 32-bit RISC CPU(ARM9) 
RAM 8MB SDRAM 
ROM 512K 
Sound 44.1Khz 16 bit Stereo Sound / 4 Channel Wav Mixing, 16Poly S/W MIDI Support / Earphone Port / 2 Speakers 
External Storage Medium Smart Media Card (SMC) 
Wireless Multiplayer Gaming 4-Channel RF Module 
PC Connection USB Port Connection 
Power Supply 2AA batteries (12 hours use time between charges) / DC 3V Adapter 
Option Rechargeable Battery 
Controls 8-way directional pad (joystick) + Durable 6 key button 
MP3 Capability MPEG ( I, II) Audio Support 
Other Add-on Applications Image Viewer, Text Viewer, Media Player, E-Book Viewer 
RF Module 2.4GHz ISM Band 
NINTENDO GAMEBOY ADVANCED
CPU  32-Bit ARM with embedded memory
DISPLAY:  511 simultaneous colors in character mode and 32,768 simultaneous colors in bitmap mode 
MEMORY  32 Kbyte + 96 Kbyte VRAM (in CPU), 256 Kbyte WRAM (external of CPU) 
SCREEN  (diagonal) reflective TFT color LCD 
RESOLUTION  240 x 160 pixels 
Lik-Sang rates the power of the GP32 as 4 times the CPU power of a Gameboy Advance (GP32 up to 133mhz? Is that correct), but I do not know enough about both ARM processors to know if this is factual. 
hmm... requires a ton of investigation, which I am sure others are already well ahead of me (and more accurately doing so). 
HZ 

h34r: