A leaning Spyder, should be built. I ride a snowmobile every winter all winter, for the past 20 years, and I strongly feel the Spyder's on real flaw is it leaning the wrong way. I love my Spyder, but it acts like a centifuge, and that's not ideal. The fact is they could narrow it by a foot or more, improve the whole riding experience, and have fewer drawbacks. I am buying the next big name brand leaner on the market. I'd like a Honda Neowing, but I'd bet money Yamaha gets to the market first.
And some of the comments above are pretty uniformed...."haven't seen a successful leaning trike"? In the Internet age we live in that is just a display of ignorance that leaves me confused. There are many scooters and aftermarket leaning trike conversions that make our Spyder's look like 60's technology.