I just recently sold my last Goldwing and bought a 2014 RT-S SE6 after doing long distance touring on Goldwings for 14 years. I made the switch because my knees are getting too bad to hold up myself, my wife and an 850 pound motorcycle in traffic. I have only had the Spyder for a couple of months now and I really don't have enough experience to offer a really good comparison. I will just offer a few one-liner observations not in any particular order.
* The Spyder provides a much more relaxed experience while still providing most of the feeling of freedom you get from riding a 2 wheeler. I think that can be said about any trike
* It is more difficult than you might think to adapt to a 3 wheel vehicle when you have ridden for many years on two wheelers. I know what you mean. We made that transition in 2006. I am just getting comfortable after 800 miles.
* The Spyder powertrain does not in any way compare to that of the Wing. The 1800 6 cylinder is much smoother and has more low RPM torque. The 1330 is more than adequate though and I kind of like the 3 cylinder rumble.
* I got the semi automatic push button gear shifter option, mainly because I wanted the big OEM floorboards. After using it a while, I have come to like it, although I would still prefer a clutch.
* The amount of on board storage is more than the Wing Really??? The only thing you gain is the funk, and that isn't very big. and is going to be a great benefit to me for short 3-5 day trips when I don't want to pull a trailer. The wife dislikes trailers. Plus, we have no room to store it.
* There aren't nearly as many accessories for the Spyder as the Goldwing and the BRP ones are outrageously expensive. The after market industry seems to be catching up though.
* I do all my own maintenance and the Wing is considerably easier to work on and has fewer maintenance requirements than the Spyder. So far, this has been the biggest disadvantage I can think of. I was told by a Spyder Service Manager that an RT is more expensive to maintain than a Wing because of having to remove the tupperware to do anything. Having a 90 minute drive one way to my dealer with the best reputation is my biggest issue.
These are just thoughts right off the top of my head and are not backed up with a lot of experience. I will not be able to do a really good comparison until I get maybe 10,000 miles on the RT. If you have any specific questions I would be happy to try to answer, although there are others here more qualified, including our forum sponsor Lamonster.