A few years ago, I too had to make that: “quit riding/down scale/or trike decision. I am now on my second trike and absolutely love it. As you pointed out, there is a learning curve, for me the transition to my Gold Wing/CSC trike was minimal. The biggest thing to remember is rather than leaning (2 wheeler) into a turn, you push & pull (trike) into the turn. My CSC conversion has “PowerTrak” which is a 6* rake and makes a huge difference. Granted, triking requires a little more effort than 2-wheel’en but it’s just a matter of getting accustom to.I've only had a Goldwing for going on 4 years, but at 76 I find I have been thinking a lot about where to go where I have to admit that I am no longer up to handling this 900 pound bike. Sitting here today with a bad case of the flu, making me feel every bit of my 76 years, makes me even more sure that the day will come when I will face one of two choices: go to a trike or accept riding a much lighter and easier to handle motorcycle, even if that means giving up so much of the luxury that I am now used to. Triking a Goldwing has some appeal, but after having a chance to ride a trike last summer, albeit only for a very short ride, made me realize that a trike is a very different experience from riding a motorcycle. So assuming I am recovered enough by this weekend to no longer be contagious, I plan on going to the motorcycle show in Chicago and at least getting to sit on some of the possibilities for my post-Goldwing days. Being a former Triumph rider, the Street Twin has a lot of appeal, as a "standard" that reminds me a bit of the old Honda Nighthawk 750. The Honda CB500F is another possibility, and there probably are a few more that meet my criteria of being light, having a low enough seat for my 30 inch inseam, and having enough capability for some time riding on the Interstate. There's nothing like getting really ill at 76 to focus one's mind on aging and mortality, but I am a long way from even thinking about giving up riding.
My suggestion would be to ride as many different conversions as possible, spend some time over in the trike sub-section of this forum and ask a lot of questions.
Good luck with your decision,