I converted this into proper OO C# and it runs great. I was able to get a score of 490. I found that the DNA strand you provided in the TSQL for a score of 480 doesnt work as you would expect because of the random genes. What you have to output is the action path resulting from the DNA strand.
It is true that if you removed the random gene, you woudl get more consistant results, but if you think about the way that humans are, you would realize that you would be removing the human element form the system. Doing so may or may not be a good thing
I think that modifying this GA code in certain ways would benefit specific requirements and would not fit every solution.
I've already implemented walls and other items as well as robot memory with some very interesting results.