Sorry for the not using the standard conventions but I just want to get to the details quickly.
Firstly, the VoIP can only be used (without jitteriness) with OpenAL enabled, but OpenAL's 'realistic' exponential sound intensities can be painful in combat and can be too quiet when further than 500 units. It would be nice to allow it on SDL or whatever the vanilla setting is. Whenever I use VoIP, I don't play. Whenever the map changes, I just noclip outside the map.
Secondly, VoIP needs its own volume control. The "/voip gain <playerID> <volume multiplier>" also doesn't work so I can't really hear people when I'm playing in combat.
Thirdly, can you add the option 'all' to the voip send targets menu?
edit:
##thly etc.etc. (I'll just add others here):
-Option to adjust codec bitrate (server/client, whichever)