I tried the official 8.0.2 build on my RPi2, seemed a lot better than before in that channels were actually watchable again, but still getting occasional green gunge (continuity errors in Tvheadend), and for whatever reason Channel 5 HD (UK Freesat) was a total garbled mess - so bad it would crash Tvheadend completely. Using "MMAL - advanced" deinterlacing.
Trying smp's latest build (without media_build) now - much more stable (Channel 5 HD will play OK) but still occasional continuity errors when playing live - 8 errors in about 15 minutes from testing just now (BBC 1 HD). I tend to watch recordings more than live, which seem to have less errors (lower load I guess) - though it can choke if for example I'm playing some other video while it's recording.
there is a official 4.2 packages from Tvheadend since ~2weeks now
They need to update their website then : AptRepository - Tvheadend
I'll try if I have the time.