The Main differences in the 14 and 15 models from what I see is just a few extra options on the 2015 and slight gas efficiency increase but cost differentiates the options
I have a 14 model that I like a lot. Just keep in mind that it is made of plastic or a plastic fiberglass blend so you need to take extra care for it. I've gouged it on the dock and had to make a repair already.
The Minor fixes your speaking of (the rubbing engine wires, handlebar recall, engine cover ect) should be taken care of by the dealers by now as they know the bugs that were originally not part of the installation process but now are.
If you can save a few grand on a older model I'd go for it but if the price is similar say 1500 to 2k more I'd go with the 2015 especially if u are gonna want to install VTS like me lol
about storing it I don't store it at a marina or a warehouse I stored in my garage which is unheated it gets down to about 35 degrees in there 32 degrees but I do a meticulous winter maintenance and make sure it's all set prior to going cold
If you have the $cake$ go to a marina that's insured for sure
You can keep it anywhere if you do the winterization correctly
Flush, drain all water, add antifreeze to the water box, spray xps lube in and on all metal parts and fill gas tank and add stabil
So yeah sparks are really fun and easy to maintain go for it