WaveShield vs VoiceShield

Hi,

I'm considering this two shields to make my arduino talk, and before buying I would like to know some opinions on both.

I'm making a project in which I have to send various sensors data to a mobile phone, right now I'm doing it by SMS through a GPRS module but I would like to be able to make a direct call to the module and ear the arduino reading the sensors values.

I'm using arduino mega, and right now I'm already interfacing a SD card for datalogging, so I don't know if this can interfere with the SD card on the WaveShield in some way... I would have two SD cards using two different libraries! Is that even possible?

The WaveShield seems superior, but I only need to read some data and VoiceShield seems easier to develop with...

So, what do you guys think?

Thanks,
Sergio