1) the affiliate link points to YOUR URL, so I suspect you get more Google pagerank from this.
2) because of the above, your affiliates won't use links that look like obvious affiliate links anymore
3) You can create multiple sales pages and let your affiliates choose which suit them best.
Using this tool would make me seem like a better product vendor that cares about affiliates (the truth), so it could attract me more affiliates.
If, over the next year, this generates me even a few more sales (given that I pay 75% commission), it will have paid for itself.
I think it was a good investment. Not sure why everyone on CB is not using this product.