Nick, I just shot some Efke 25 in 11x14. It is only one sheet from a recent trip to Joshua Tree NP. here in California. It was very blustery the whole time I was there and only exposed one sheet. I always develop in Pyrocat-HD and use the 2:2:100 dilution and develop one at a time in trays. I will have to check my notes and I will post the times/temp later after I develop the sheet tonight.
I have used the FP4+ and it is great in 11x14. The Efke 25, 100 is in stock at Freestyle.

Jim