asterisk users - May 2005 - Optimal prompt format (gsm, ulaw, wav) for quality effeciency space

I'll summarize on http://www.voip-info.org/

What's the best way to store static prompts in Asterisk?  The system 
prompts are provided in gsm
format.  But we have no limits on disk space.  Is there a better 
format?  If we provide clips
at 8 bit 8000Hz mono ulaw, and our IAX connection matches, do we gain in 
speed, efficiency, and quality?  Will Asterisk search for the best 
matching clip, if we provide several formats?

Do I have the sequence right, for a the media stream of a voice clip?

GSM format on disk.
converted on the fly to uLAW by our Asterisk box
Transmitted via IAX to a (Broadvoice, LiveVOIP, VoicePulse) data center
converted on the fly to ????
Transmitted via SIP to a (Level 3, RNK, XO) data center
Transmitted to a point of presence
converted on the fly to TDM
Transmitted via the PSTN
converted on the fly to analog
Transmitted via last mile copper
converted to sound waves by a telephone
converted to brain waves by an ear

Some of our prerecorded clips sound OK at the end.  The clips generated 
by Festival Text-To-Speech  sound like an Edison wax cylinder was used 
an an intermediate codec.  Try 970-688-4348 and enter code 511#.

Obviously we'd like high quality, and lack of dropped voice packets.  In 
our particular case latency is not an issue at all, the user is simply 
hearing a mesage.

                            -Bryce Nesbitt