I saw the two-move cut I was missing right after I found the 311 record. :-) Niels, this one may be your best one yet.
I'm 95% sure it's optimal. For the record, 27 attempts.
I was 2 moves off when I got 433. Cant remember the path I used. I found a nice pipelining shortcut. :-) May not be optimal, but its about the same as YFKDs record.The levels not great but its depth to it that I dont understand. Current record has 3 or 4 transpositions.
Pretty tough: it took me fifteen minutes to figure out how to get through it. Not broken, I don't think, just closer to optimization. You will probably be able to find this route or better.
Insights