If you are hesitant in any way, I would just walk away. Numerous reasons why someone would get rid of a motorcycle and your hunch might be right on this one. There are too many great deals around for you to feel you have to jump on this one. I would hate for you to kick yourself over and over for a purchase you had a bad feeling about and went through with anyway. Good luck whichever way you decide to go.
I say the same there are lots of 6s for sale. My 13 has 45K on and I never had a ghost shift but he transmission is very rough with down shifting if I dont pay attention. Have to have very positive pressure or the shift is very rough and yes it has gotten slightly worse over the years.
Guess I got lucky and so have a lot of friends with the 13.....I have 58k and zero issues with the transmission. Only thing I can complain about is the "cold stumble", but others I know with the 13 dont have that issue. I would and have recommended the 13 model to friends and family. I have been on this board a while and its really the first time I have heard about 13 specific transmission issues.
As been said here very few 13 and below goldwings have had tranny problems.My 13 F6B needs me to give very positive shifts with my foot and they are just clunky trannys.Many including a couple on this site have well over 100k without a problem so I really do not see the worry.Also there have been 14 and 15,s with the so called upgrade that have ghost shifted.Good luck with your search.
Personally, I would not let worries about the "ghost shift" stop me from buying a 2013 bike. My 2014 has had the occasional ghost shift since I first bought it (new), despite shifting firmly and intentionally. There was a change between 2013 and 2014, but it didn't 100% remove the issue. In addition to jumping from 4th or 5th to neutral between the two without touching the shifter, occasionally when in 4th gear and attempting to shift to 5th, the shifter feels like it's already in 5th (i.e. there is no "catch" in the shift assembly to move the dogs to put it into 5th. ). Simply re-engaging the clutch and rolling out of the throttle (taking out the lash in the drivetrain) makes it grab the shift forks and we're back in business. I've never seen evidence of damage (no debris in oil in the 6 years I've had her). I suspect there is a minor alignment issue with the shift forks from new. Despite the occasional bike that has this "character", I'm not aware of any bikes that suffer a full-on failure. By contrast, I regularly ride with another member of this forum, who bought his 2013 new, and I don't think he's ever had a ghost shift. YMMV.
With regard to cruise, I agree that 15 was the first year, but for ~$250 one can add a Rostra electronic cruise, and it's not a bad job. I've done three of them now on various bikes.
Kind Regards,
Russell