For Aggregation or Bonding it does require setting up the Peplink Site to Site VPN between 2 Balances, models 210 and up. The Balance 30 is not able to aggregate connections of any type (3g/4g, wired, etc).
Outside of the Peplink Site to Site VPN, the Balance is just that, a session based load Balancer, which can give a more efficient use of Bandwidth (especially in a multi user environment) due to using all available WANs (including 3g/4g)for traffic. Also for downloading files with a bittorrent or download manager you will see faster speeds due to being able to open multiple sessions using all WANs.
But if we are talking a single user going out to the internet, the speed of the session is going to be tied to the WAN it originates on. To help illustrate further, take a look at the following links from our Knowledgebase-
Article-”Combining the bandwidth of all WAN links. 3M + 3M = 6M?"
Article-”Understanding Peplink Site-to-Site VPN"
Once you have the Peplink Site to Site established, the VPN is treated as if it was one large pipe that has all the WANs in it. What this mean is that traffic in in the tunnel is broken up on a packet level and is going to use all the WAN connections. Once it gets to the other side, it gets reassembled and sent out of the Balance.
I do hope this helps to clarify matters Gustavo, let me know if there is anything else to go over.