If you plug your mod mic into the X7, the quality of the X7's ADC should out-perform the ADC built into your motherboard. There shouldn't be any latency with the mic recording due to the X7, the only cause for latency would simply be the chat software you use and the Internet. I've had good experience with Mumble for chat, but it was good enough that I haven't bothered comparing to other options.
I haven't listened to the other DACs you listed... but the performance should be pretty similar.
I haven't listened to the other DACs you listed... but the performance should be pretty similar.