My cpap has c-flex which means that the pressure temporarily reduces when it senses exhalation and this works quite well for me. I can adjust it up or down depending on my difficulty exhaling.
I had bipap when I was having trouble exhaling against cpap in the ICU, but I couldn't tolerate it because I could not keep up with the rate they set it on and it felt like my lungs would burst.
Given the correct settings it would probably be beneficial to have bipap. My pulmonologist suggested it, but given my bad experience with it, I declined.