@bmarkus At least in the EU region, RX2 on the standard frequency has the advantage that it allows for a much higher use (10% duty cycle vs 1% in most other bands), and much higher power (if the gateway allows it). Depending on your data rate mix, you might be better off in RX2 than on RX1
RX2 is using a single channel with low data rate. It is obvious, that RX1 using 8 channels and various data rates, specially set automatically by the ADR algorithm offers much higher througput than RX2. Why to demage network performance if not necesary?
It could be even better if the gateways allow higher transmit powers and you can use faster data rates than the default on RX2.
Not sure I see the link between RX2 and 3G backhaul, unless you mean you need the additional time, but one could set RxDelay to a higher value for that (though that is definitely not a good thing for battery life) rather than pick one window over the other.
3G connections typically offering longer latency than 1s which makes RX1 unusable, and usually changing rapidly even going up to 3-5s.
In a production environment it is not a good practice to change RX1 timing anyhow.