I had been looking for a folder light enough to carry on public transit and on the plane as checked baggage along with my other gear when on business trips. I have owned many folders over the years including Dahon, Tern, Tobukaru, and Downtube. All of them were 406 or 451 wheeled bikes. They all disassembled to fit in a standard 31" hardcase albeit with some necessary dismantling. Because of the folding geometry, I found that I had to remove the wheels, handlebars, rear derailleur, and often I had to dismantle the frame. All of this work before and after my journey required me to carry a small toolset with multiple wrenches, spanners, and Allen keys of the same size with me. Since the bikes weren't designed for this type of repeated dismantling, the important parts would wear down quickly.
I debated getting a Brompton for a long time before selecting the Solorock Spin 3 thanks to AccuNeal's detailed review and testimony. I decided on a 16" wheeled folder because I would not have to dismantle the frame and remove the derailleur. Removing and reattaching the wheels as well as the handlebar is short work with a folder. I like that the Spin has a derailleur. Over the years, I have had trouble with IHG setups. They work great when they work. However, adjusting them is a pain. Derailleurs on the other hand, are easy to adjust and cheap to replace.
Since getting the Spin 3, I have added the Dahon Luggage Truss and Dahon Luggage Carrier to the front and removed the rear rack. The front load stabilizes the bike. The luggage truss/rack combo is rated to hold the same weight as the rear rack. I have also replaced the stock pedals with folding pedals by MKS.
I have ridden about 60 miles since buying the bike online from Solorock. As with AccuNeal's testimony, the bike handles beautifully. The steering is not at all twitchy as it is on a Brompton. In fact, it rides as well as my 406 by Downtube. With a 15lb backpack strapped to the front luggage rack, the ride is rock-solid. I am 6'3" in height and weigh in at 210lbs, so I am at the upper limit for the rider specifications. The bike fits me very well. I have plenty of options on handlebar positioning from low aero to upright and casual. The seating position is about 1" shorter than where I would like it, but this is still taller than the stock seatpost height on a Brompton.
My main reason for choosing this over the Brompton is the purchase and maintenance cost. I have found that TSA agents are really curious about the contents of a suitcase containing a folding bike. Without fail, my suitcase is inspected by them. Then the re-packing job by them is probably done with great haste and the result is less than ideal. In the past, my other folders have suffered some damage at their hands such as scratches to the frame and damage to the spokes. My suitcases have also suffered damage at their hands. The Spin 3, with its standard components is a better purchase over the long term rather than a Brompton with its custom, limited replacement parts. I have not yet taken it on a business trip. However, I have experimented with packing it away for a trip. After removing the wheels, seat post, and handlebars and handlebar post (think upper T), I am happy to report that the bike fits into my 31" hardcase beautifully with room to spare for my helmet, shoes, smaller toolkit, pump, tubes, luggage rack, lock, and clothes for the trip. All of this weighs less than the 50lb checked in baggage weight limit. I'll be sure to share my experience after my first business trip with the bike later this month.