I don't usually get into technical discussions on this blog but I thought it might be worth while to continue the topic started on Jack Rickard's EVTV blog. Simply put Jack has stated that pushing the voltage of a LiFePO4 cell above 4.3 Volts, the breakdown voltage of the electrolyte, will not harm a cell if the cell is not full, and that in fact there is no such thing as electrolyte breakdown voltage. This of course flies in the face of just about everything I've read on the topic, and even contradicts what battery researcher Jay Whitacre states in his LiFePO4 battery lecture video, a video that Jack actually provided a link to.
Go to the 50 minute mark in Jay's video and listen as he talks about electrolyte solvent breakdown above 4.3 volts, equivalent to water electrolysis at 1.3 volts. If a cell voltage is held above the breakdown voltage of the electrolyte the components of the electrolyte begin to separate out. This can happen even if the cell is not yet full. In normal use this should not be an issue, but it is something to be aware of.
For further technical reading about electrolyte breakdown voltage there is this rather comprehensive review by Kang Xu: Nonaqueous Liquid Electrolytes for Lithium-Based Rechargeable Batteries
The pertinent information starts in section 5.2 page 4325