So I just checked London-Kazan return for random dates in January. Booking with KLM (LHR-AMS-SVO-KZN) is GBP271. SU is GBP341 with the single connection in SVO. Flying Blue is more suited to my other travelling needs so booking with KL for 10 extra XP in this case could make sense.
As SU doesn't currently codeshare to Izhevsk, booking with SU is the only single-booking option available but for the same random dates LHR-SVO-IJK is GBP382 as opposed to GBP299 booking LHR-AMS/CDG-SVO and SVO-IJK separately. Were a code share to be established, I would expect the fare to be similar to the Kazan one and the connection in Moscow would be protected.
ok , so it seems you found a nice spot , in fact i checked and KL prices + extra 10XP sounds nice , thanks !
In my cases , from various airports , SU flighs to domestic airports are 50% more expensive than "neighbour" foreign cities.