Understood, but those Sierra-2EX crossovers are designed to "see" Sierra-2EX drivers only and only within the Sierra-2EX cabinet. I want to make sure you understand this. It is very precise, even a change in baffle size, or driver to driver spacing requires crossover changes. This is critical with a speaker like the Sierra-2, because the high pass and low pass filters do interact with each other and it is possible that simply swapping in a different woofer could result in lowering the crossover point which could end up causing unwanted frequencies to reach the ribbon tweeter, possibly resulting in damage.
Obviously, you have a great interest in speaker design and I encourage you to continue experimenting. There are many good books out there that you can learn from with regard to crossover design and how to best match and "pick" off-the-shelf drivers to reach the performance goals you are after for your design. The ability to take proper measurements is critical though, and without that - even though to your ears something might sound better, expectation bias is real. Since you believe in measurements, I had previously offered to measure one of your modified speakers on our NFS free of charge (you are responsible for shipping) - that offer still stands. Companies often pay up to $2K for this type of service.... Wouldn't you like to "see" the performance of your creation?