The statistical properties of Composite Triple Beat (CTB) and Composite Second Order (CSO) distortion terms associated with the analog channels carried on Hybrid Fiber Coax (HFC) are presented. Both simulation and measurement results show that such distortion components falling on individual channels have amplitude Probability Density Function that is nearly Rayleigh distributed (having a Standard Deviation of 5.7 dB). It is shown that both CTB and CSO components have peak envelope power fluctuations that exceed their average (measured) power levels by more than 15 dB. The temporal statistical properties of these distortion components demonstrate peak envelope power fluctuations with characteristic times on the order of 100 microseconds. The implications for 256 QAM digital downstream channels on which such CTB and CSO components fall are discussed. It is shown that some currently prevailing link budget design practices leave margins for reliable 256 QAM operation wanting. This deficiency appears particularly in systems that are rich with Narrowcast combining of digital channels such as cable modem and Video on Demand (VOD) applications. Several mitigation strategies and improved design practices are suggested. These involve physical layer choices for deeper digital interleavers, establishing downstream QAM frequency offset relative to the analog channel grid, improving CTB and CSO specifications for cable modems and digital set-top tuners and adopting tighter aggregate noise floor specifications for head-end RF transmission gear.