Greetings,
Ok I try to answer some of your questions from my point of view. I have a 2012 Goldwing with a 2015 MT razor kit. As far as reverse it will be the Honda reverse (Neutral then reverse switch, then start button). The rake kit I don't remember the degree but get one installed. Mileage depends on your riding style and roads. I like backroads so that keeps my speeds down, thus rpm's down. on highways rpm's go up mileage goes down, but i average about 32-34 mpg. Maintenance depends on what you do yourself versus taking to the shop. I work on my own bikes and so far i've done most of it myself. I did have to take it to the shop to have the kit bushing replaced (700-800 depends on shop). Comfort is great provided you've upgraded to your comfort, I upgraded my seat to sit back a few inches and up a bit. I can do 10-12 hour days stopping for gas and meals.