from my experience, i have rarely lost any items, more often then not its caused by micro blocks around the interface, blocks are shot way out of sight some times ending up under ground, a simple way around this is having an input chest and an output chest, having the items drop out of the system is not the best way to use the system but it looks good and takes up less space as its only one input chest.
as far as crashes are concerned, nothing has happened to me yet, but that's for the warning, ill keep a close eye on it