Just thought I'd throw this post up as it might let some people rest easier after throwing a sachet into their fv and hoping they shouldn't have rehydrated instead. After reading so much over the years on the fierce battle between the old rehydration vs no rehydration camps and after reading what I considered an extremely dubious call by Jamil Zainasheff that pitching dry yeast straight into wort would lead to up to 50% loss on viability I decided to see what a few yeast packets of lager yeast 2 years past their best before date would do in 30hL of wort pitched straight through the manway of the fv. There was no concern from anyone at work that it would be an issue and it was a small one off batch either way so we went ahead with it. 24 hours post pitching we had passed the lag phase and the beer was fermenting and I ran a viability check and got 96%. Just thought I'd throw another data point into the ring for everyone to consider.