Today I upgraded from a Honda ST-1300 to a K-1200 LT -- I picked up a new (to me) K-1200 LT from Dallas and put about 320 miles on it getting back down to Austin the long way. I drove in stop-and-go traffic, deserted back roads, and a crowded interstate, so I think I had a little of everything. I wanted to share my impressions of the differences between the two bikes, in case anyone is considering both in the future. Obviously, my assessment is going to be a little biased.
I'm going to use LT and ST for brevity.
Power: The LT clearly has less power. This was expected, since it has a smaller engine and weights 200 lbs or so more. I didn't really have a problem with this; I still had plenty of power to accelerate for passing while doing 75. The ST was really overpowered to me -- I was afraid to actually open the throttle all the way because I would not be able to hang on.
Engine Sound: A lot of people don't like the way the ST sounds, likening it to a sewing machine. I didn't mind the sound on the ST; it just sounded like a fine machine to me. However, the LT certainly sounds more like a "real" motorcycle.
Low-Speed Handling: I was paranoid about the LT because of so much discussion about it being top-heavy. However, the low-speed handling on the ST and LT seemed pretty much the same to me.
Cargo: I love the trunk on the LT. It is so much easier to access things when they are horizontal. I also like that you can latch the cargo without having to lock it. On the ST, you can't close the saddlebags unless you lock them. The ST also has a battery issue related to the saddlebags. To get to the battery, you have to remove one of the saddlebags, then remove a piece of fairing using a hex wrench. This gets you in a weird position where you need two keys in order to jump-start an ST. The LT is much better in this regard. The ST has more cargo room up front, with two separate small compartments, one locking and one not.
Cruise Control: The ST doesn't have it, and I had never tried any of the after-market stuff. But I LOVE cruise control. It makes the long trips SO much nicer.
Handling. The LT seems to handle turns a lot differently. It feels like it is on rails. I don't know why. The ST always felt a little uncertain when I was taking a fast turn.
Heated Grips/Seats: The ST doesn't have these. I haven't ridden in the cold, so I don't know how much of a difference this makes. I did have my butt roasted for several hours before I figured out how to turn it off.
Radio: No radio on the ST. I have to admit that I thought putting a radio on a motorcycle was a totally stupid idea. I didn't think you would be able to hear anything at highway speeds. However, it totally works. The sound actually seems like it is coming from inside my helmet - freaky! And it gets quiet properly when you slow down. However, it is dumb that a motorcycle built in 2009 has a CD player instead of an MP3 interface.
Windscreen: The ST has a motorized windscreen almost identical to the LT. However, on the ST when I raised it to the top level, it created this weird vacuum thing which felt like someone pushing down on my head, so I could never raise it all the way. No such issue on the LT, and it gets nice and quiet when the windscreen is raised.
Fairing: The LT fairing seems to do a good job of deflecting most of the wind, but the ST fairing does as well. I like the additional adjustment vanes on the LT. The ST has a horrible heat problem that will bake your shins. No heat issues on the ST.
Seat: As expected, the LT seat is a lot more comfortable that the ST seat, and has some lumber support.
Reverse: Not on the ST, obviously. I thought this was silly, but I did use it today when I parked on a slight incline. It was nice to have. I tried to back up the normal way and it just wasn't happening.
Power center stand: Not on ST. You don't really need this on the ST, but it was very nice to have for those extra 200 lbs. I think I could do without it, but I like having it.
Gauges: I actually likes the ST instrument panel better. Big tach up front, and digital speed readout. I usually want to know my exact speed. On the LT, there is a speed marking for 40 and 60, and this only covers about an inch of range. It is hard to interpolate whether I am at 50 vs 55. I found myself using the GPS to figure out my actual speed.
GPS: I had a Zumo 550 on my ST and the LT has a nice built-in Zumo 660. I haven't explored all of the options, but it does two new things I really like: First, when you are navigating it tells you which lane you need to be in. Second, it shows the speed limit. I found this to be really accurate - it would change the speed limit on the screen, right after I passed a new speed limit sign.
Overall, I spent about 6 hours on the bike today, and I do have a little bit of a sore back, but otherwise great. I'm really happy with the new bike.
Also - kudos to Dream Machines of Dallas. Those guys were great to work with.