I've never grown the original Wedding Cake(s), and this is my first run with Cake n Chem. At day 30, it's way to early to know. Just because the Cake n Chem's aren't stacking like the Copper Chem's doesn't mean there won't be some good, great or comparable yielders. The Cake n Chem's may not stack up donkey dicks, but they could produce rock hard golf balls. Smaller dense nugs can sometimes be equal to larger less dense nugs. For example, the Super Lemon Haze from Greenhouse that I grow puts out K2 footballs. Gorillas Glue #4 in my setup puts out a lot of golf balls, pebbles and marbles. However, they both tend to average the same yield. That being said, GPS has "Tags" under the pricing of each strain. Copper Chem has a tag titled "Big Yields." If you click on that you'll see all the strains that have that tag. It doesn't mean that others won't yield big, but it's a common trait with the strain.
Sound like you want feminized. I'm certainly not the expert on that, and I've never grown any GPS feminized. Looks like others have info for you. Don't over think it. GPS has great gear. Choose something, have fun, accept the outcome without regret. Good luck.