We as hobbyists, semi-pros, and pros all have an inherent desire to experiment. I personally had done this with chemicals, techniques, and methods. Machines are in a category thats a non negotiable for me. I always am a fan of purposed built machines since they were designed with a specific task in mind. They just seemed to work better and more efficient. The notable exception would be the Porter Cable DA. The original (first gen) Porter cable polisher was a DA wood sander. While it served a purpose at the time, any today's purposely built polisher would put it to shame.
I have to be honest.... my dewalt (the yellow monster) been sitting on the shelf collecting dust. It's just too cumbersome to use. LOL My much newer flex rotary hasn't seen much action in the last few years either since I never had to deal with gel coat. I use it to jewel but that rarely happens. Maybe I been hanging out with the wrong crowd. LOL
Many of today's top notch rotary machines are full of features to increase performance. They are lighter, quieter, and generally offers the user more control. Its not hard to learn how to use a rotary but it takes years to master it. For those who are proficient with it ... no other polisher can get the job (paint removal) done faster. Most paint on today's car are very thin.... I personally have one of those thats barely measured 3 mm. A rotary will never be my first choice to use on such paint system.