What I learned is I got very lucky on my first unit. I bought a fathom without trying any other units. I actually had no interest in rebreathers at the time. I got lucky that I love the unit as much as I do. About 2 years after getting the fathom I did the sidewinder course and hated almost everything about it. It made me appreciate the fathom. I have since tried other units as well. Some I liked some I didn't. But the most important thing is I could only make that distinction due to having ccr experience. I say if you can rent a unit and take the course, do that. Try dives are a waste of time.