I managed to grenade my engine back in august but didn't do the post mortem tear down until recently. More on why that happened later.
But the first thing I noticed when tearing down the engine was the large amount of red sludge that had accumulated on the engine internals.

I switched to E85 in august last year and have since attended 4 trackdays plus a great deal of road tuning. My guess is about 10-15 tanks, or about 400l
AFR for WOT was 12-12.5:1. Cruise 14.7:1.  Stock ECU remapped for E85 and ID1000 injectors.

Some pictures with comments:

This is the TumbleControlSystem after 2 trackdays. This part is actually upstream of the injectors but still has the red discoloration.


Intake channels. Lots of deposits.  Also some buildup on the valve stems.

Pistons has the same red discoloration on the dome:

And here is the messy stuff. Piston rings and skirts are soaked with thick red sludge. This definitely has an effect on how the ring moves and how the oil ring scrapes off the oil imho. The middle ring was almost stuck. 

Rings removed to inspect the oil holes. Seems ok but this could potentially block the oilchannels to the piston pin.

This thread on evolutionm.net describes the same problem:

This post by arghx7 has some references to tests performed by Saab on the GM Ecotec eninge using E85  http://www.evolutionm.net/forums/evo-engine-turbo-drivetrain/486458-3-tanks-e85-look-my-id2000-s-unreal-7.html#post10189502

I don't know if E85 had any part of mye engine seizing up but the oil was definitely diluted by a lot of E85.  Right now Im leaning against going back to 98RON and adding WI.  It sucks loosing 5% energy content for the same AFR though but fuel availability and possibly reliability makes up for it imho.