well, a small change might be something that requires huge amounts of memory, or even to use diskspace in order to be calculated, which makes the use of GPU so slow that CPU are still usable for mining. (take a look at the momentum algorithm used on protoshares, miners are only 2 or 3 times faster on GPU).
Requiring to use disc space is surely not a small change. Their whitepaper seems to be outdated, when reading it the first thing I thought was that you can use bloom filter to significantly reduce memory requirements. Some googling revealed that someone else already pointed to this and other vulnerabilities in the proposed scheme were found. They seem to fixed them to some extent but its not fast to find any definite information. This all will require time, I can't just copypaste some code into SpreadCoin without understanding it.GPU miner is my priority now.
