Wilburforce - 11:06 pm on May 27, 2013 (gmt 0)
Does anyone see any problems I may face by doing this?
I wouldn't change anything without waiting (for weeks, not hours) to see whether the other site maintains a good position.
Because "add to cart" is in such widespread use it may have immunity to keyword stuffing that other phrases do not have, so I wouldn't be confident that a block replacement will have
1. any positive, and
2. no negative
Knee-jerk responses to Google are more likely to do harm than good. I would say "concentrate on the end-user", but I'm not sure that works any more.