My Library as of 11/2014:

4368 albums
1562 artists
55178 Tracks
1433 GB used

Using MC200 (no storage utilized) and QNAP TS-469L configured RAID5.

Main system: Cable, Apple TV, HD621, G68D, AC11, 218, DSP7200SE (L+R), DSP3200 (L+R Rear)
2nd system: Cable, Apple TV, MC200, HD621, 568.2, M3100 (L+R)