I do lots of the creative textured yarns, and love the Mach III for those, because of the low ratio and the super-jumbo bobbin. When I'm traveling/teaching, I use the King Bee, which can do pretty much the same things as the Mach III, just in a smaller skein (small is relative though -- the 8 oz. bobbin on the King Bee is still twice as big as most other wheels bobbins).
The Firefly I primarily use for churning out singles that end up being plied on one of the other wheels...its ultimately portable (for when I'm traveling with the family and have NO ROOM) and also great to spin on when I just feel lazy.
I recommend Spinolution to everyone -- which wheel depends a bit on what type of spinning they play to do and their budget. I'm a dealer -- have sold these wheels to brand new beginners, people with health/mobility issues, hard core 'art yarn' spinners, as well as your typical spinner wanting to make knitting yarns.
I was a loyal Schacht Matchless spinner for over 15 years, making miles and miles of smooth yarns for knitting. Then I got bored, discovered the world of creative textured 'art' yarns. At the time, Schacht did not have a jumbo flyer of any kind for their wheels, so I started searching for another wheel. I tried several different wheels, but they all fell short. I was spoiled by the quality and reliability of my Schacht wheel.
Then I heard about Spinolution wheels. It was very early on... Mike had just introduced the Mach I, and was selling it unfinished and unassembled. Having never seen one in person, I was nevertheless intrigued, ordered one and quickly fell in love! I've worked with Mike off and on through the years to help refine and further develop these wheels (my suggestions lead to the introduction of both the Echo and the King Bee wheels). I really really love the responsive treadling, ease of changing bobbins, and innovation that these wheels have to offer.
Melissa Yoder Ricks
SpinOlution Dealer, Front Royal VA
Wild Hare Fiber Studio