I have heard of Sergei Lyapunov, and I have concurred that he was indeed a gifted composer who unfortuantely could not stand the test of time and indeed is nearly forgotten. His most famous work, the Transcendental Etude Opus 11 #10 "Lezghinka" is popular as a virtuoso showpiece, though it is far more in terms of its musical content, which indeed is impressive. A nationalist, Lyapunov's work reflects an interest in barbaric Russia before the advent of Christianity and of the orient and far east. He was a very skilled composer, with excellent craftmanship and a fiery, inspired musical disposition.
For those who are interested, here is a link to download "Lezghinka" from the SMA: http://www.sheetmusicarchive.net/dlpage ... on_id=2117