I don't believe it wise to currently view a large touring motorcycle as an investment. They are primarily purchased by older people (i.e. not 25 year olds) and the demographics are that there will be less people to sell them to when they come back onto the market. There is a trend in the UK at the moment with renovating classic cars and bikes because of a demographic bulge of people retiring and looking for a hobby, but the price spike the buying is causing will turn into a bust as the buying market decreases and the renovators eventually pass on their work.
I bought a K75 over 10 years ago and i think it is now worth exactly the same (actually slightly less, because of inflation) but I have no regrets because i enjoy both riding and maintaining it. Suggest you choose your mount on the same basis.