Valhalla has had lots of issues this year.
Boats sinking with riders in on more than one occasion, there was one instance where riders had to evacuate themselves from the boat due to the water being waste deep!
Bumps between boats, this does happen from time to time but it shouldn't do with Valhalla's ride system, also bearing in the mind the ride hardware was designed to run 20+ boats and bumps when running 8, not good. I have experienced a few bumps and it can be quite brutal, bearing in mind how heavy the boats are.
Issues with the block system around the first turntable (I experienced this first hand).
The ride hardware is knackered, all of the above have come from publicly posted reports/pictures and/or my own experiences on the ride.
Effects have been dreadful this year, most of the fire has been down all year (I have heard due to the splash from the final drop flooding the sensors), ice room not working at all, I could write an endless list of how poor it has been on my rides but I'll just say that it has essentially been a clunky oversized log flume in the dark this year.
I do not believe the rumour that the ride will be SBNO next year until it's confirmed reliably, but at the same time, there are reasons why it might have to be.