ADALM-PLUTO can be updated to extend its frequency range according to the [1]. The wiki mentions that AD9364 and AD9363 chips are nearly identical, however does not mention what exactly so that the range of the 9363 can be extended. There should be a reason why ADI does not do this themself. I suspect it is the quality control, however I wanted to be sure.
A student of mine would be very happy to get a qualified answer on this.
So I understand:
Using two Rx+Tx pairs (1) AND increased frequency range (2) is difficult to achieve on the silicon. AD9364 is based on the same silicon as AD9363 but has gone through additional testing and it does not use two pairs, so (2) is guaranteed.
Even 9363 supports two Rx+Tx pairs, ADALM-PLUTO uses only one Rx+Tx pair anyway, so 9363 can easily be operated in the increased range.
Does that make sense?
Thanks andrei_g 
I wouldn't go with "same silicon", hence the specs and the price.
Pluto revC (AD9363) can use 2 RF channel in/out pairs with extended range, but you will not get worse quality compared to an AD9361, going outside the AD9363's specified range.
AD9361 and AD9364 have similar specs, but AD9364 has only 1 RF in/out pair, comparing with the 2 pairs of AD9361.
The AD9364 config was used, back in the days when pluto had only 1 available RF in/out pair.
Andrei
I wouldn't go with "same silicon", hence the specs and the price.
Pluto revC (AD9363) can use 2 RF channel in/out pairs with extended range, but you will not get worse quality compared to an AD9361, going outside the AD9363's specified range.
AD9361 and AD9364 have similar specs, but AD9364 has only 1 RF in/out pair, comparing with the 2 pairs of AD9361.
The AD9364 config was used, back in the days when pluto had only 1 available RF in/out pair.
Andrei
