From experience, I would not recommend a long SVO transit. I arrived at SVO at 0445 hrs, got BP pretty soon but was told that I can get a lounge card only 2 hrs before my HKG flight. So I had to hang out in SVO transit area for 3 hrs which is not a pleasant experience.
The LHR-SVO service was pretty good, but SVO-HKG below par (both in C).