4G-AC55U or RT-AC68U for 4G/Dual-WAN connections

[Kretel]

Hello everybody,

I have a very slow DSL connection and want to speed it up with a 4G mobile connection. Because the mobile connection offers only a limited volume (of 20 GB), I would like to have Dual-WAN 'Failover' as well as 'Load-Balance' functionality. Both is included in the AC68U router, as far as I know. The 4G has only Failover, right?

My questions:
* Does somebody know how good or bad the 4G antenna in the AC68U is compared to the both extra antennas of the 4G-AC55U?
* Might it be possible to enable 'Load-Balance' by re-compiling the ASUSWRT firmware for the 4G-AC55U router, or is this functionality disabled because of hardware limitations?
(On a short look I could only find a switch for Dual-WAN in the code, but not the distinction between 'Failover' and/or 'Load-Balance' and why only the first is enabled or compiled into the firmware.)

Thank you!
Kretel