Yes and no. Only data available via 3rd party post will be available in AggreData. That being said, a lot of the values we provide in LiveData.xml are derived from that and will be available in AggreData (things like Projected Usage, Average Usage, Usage since Midnight, Minute, Hourly, Daily, Monthly History, etc).
What won't be available is the "Now" values that are displayed on the dashboard (usage this second, second history, etc). We don't support posting more frequently because it would cause too much overhead on both the TED5000 device AND require much more server bandwidth to accept feeds that update that frequently. Load Profile would also not be available.
As of right now, Voltage won't be available but we are looking into adding that to 3rd party posting and would become available in AggreData after that.