I must admint that I am a bit disappointed in the response from Sparkfun. Seems like I may just as well go straight to EBAY
Although some of the Chinese tend to give better support.
As for you suggestion... Here in Holland we have a saying that "multiple roads lead to ROME".. No doubt it will work. But I am not the first and more people seem to heve the same problem. On the other hand, so far I have found about 10 people with the same issue on the internet. I cannot imagine Sparkfun has only sold 10 of these shields....
I am still getting support from MicroChip (opened a ticket) maybe that will help but on my scope the problem seems either the Serial-2-ISP interface chip and its connections or the ISP software library given from Sparkfun.