To be honest ... the idea just did not occur to me! I was so fond of the idea having two radio frontends, that the whole usefulness of diversity mode in urban area did not come to me :)
So, by a popular demand, SDR MK1 is now supporting diversity mode!
For those not familiar with the concept, diversity mode means, that you can use one channel of the radio with your ordinary antenna, while the other channel can be equipped with something receiving a background noise, would it be your own laptop power supply or neighbours plasma TV. The radio then subtracting the noise from useful signal, and you will get noise canceling.
In reality, it looks like that:
(The LO frequency is actually 4.625MHz, the display is just not in sync).
As you see, there is a clear distinction where the diversity mode was switched on and off. The noise is coming from the halogen kitchen light power supplies in the apartment. The useful signal is received with magnetic loop in the apartment, the noise is received with short telescopic antenna borrowed from ICom scanner.
Please note, that this is not a universal remedy to receive anything from far away - it is not improving any gain, it is just a useful feature to cancel strong local interference sources.