I suppose this is all asked and answered. I'm on my 4th RT. I had a '99 1100 RT; a 2003 twin-plug 1150; a 2005 1200 Hex-head and my current bike, a 17 1200 LC.
Except for the '99, all these bikes were purchased new. I bought the '99 used...but in Spring of '99. You can look at the years to understand which ones I like the best and rode the longest.
I put 62K on the '99. The shocks were pretty poor. I got Ohlins for it...just great. It had surging issues, a seat that would put your boy parts to sleep. It was very hard to keep synched and smooth running. I got a new seat and windscreen; I put a fuel nanny on it; I found a little hole in the right fairing that lets you change the throttle body air screw while you are riding (don't try this at home). It's great for long interstate rides but idle is rough again when you slow down. The Amal throttle body bearings wear and then leak... It was a fun bike but a lot of work and full of little buggy little problems.
I finally got sick of fixing it. It needed throttle body rebuilding, so I traded it for the first twin-spark 1150 that came in to my dealer. It didn't surge! I got a fantastic deal on that bike. There are many issues with this bike that can't be tweaked or fixed or improved. The servo brakes on 1150s are not good. You can't stop these bikes smoothly. They are just too grabby. Also, brakes barely work when engine is off. That is surprisingly bad for pushing around a garage. Also, the foot brake is linked same as the handle, so they both do essentially the same thing. I like the option of rear brake only about 1 percent of the time. The extra 50cc's was not used for more power. Instead, they detuned it to lean-burn, which made it run hotter. One nice thing was that my windscreen, my seat and my Ohlins could be moved from the 1100 to the 1150. I got the Ohlins rebuilt and the guy used 1150 parts. I got charged a little extra, but it saved a ton. It was a pretty bike, but not my favorite to ride. I traded it as soon as the hex-heads came out.
The '05 1200 RT was a great bike for me. I had it 13 years and put 87,000 miles on it. I never had a fuel strip problem. It did everything better. It had cruise control...which is really a good thing on a sport touring bike. This sounds silly, but the bags can be latched closed without locking them. For me, this is huge. You can't do that on 1100 or 1150 bikes. It makes packing so much nicer if you're as absent-minded as me. Handling, power, brakes (new design servo brakes that aren't grabby and work with engine off). It was a graphite color with flat black shapes. I never liked the way it looked, although some other people did and told me now and then. I took a trip to CO with it and did some trail riding fully packed...went past the "Do not go past this point..." signs twice. First time, I got lucky and survived the U-turn without dumping it. Second time I went over on some large rocks at 1mph and banged up the side cases. When I got home with it, I took all the body parts off it and took them to a good body shop nearby. They sanded the side case covers perfectly and painted the bike a great black. While the panels were at the shop, I ordered clear side and rear lights for it. I put the bike back together and it was stunning...because it was all ONE color, not a bunch of broken up shapes. The lights really updated the look. '05 was, I think when Chris Bangel, the BMW designer who wrecked BMW car designs, got to do the RT. I don't know this to be true, but what's wrong with the hex-head's looks is also what's wrong with the Bangel cars....but if you paint the shiny stuff black you get black on flat black and that looks really good because the shape is really great. I did my own tune-ups with that bike. If you set the valves perfectly, you never have to adjust the throttle bodies or throttle cables. They just work and they don't change. I had the bike tuned by the dealer twice. The rest of the time, I just set valves and changed oil. Dealer always did the servo brake fluid..every 2 years is plenty because these bikes came with braided teflon brake lines. This engine is the first with little servos that keep the idle steady. They work great. These bikes, like all RT's, require a decent aftermarket seat and windscreen. I also like bar-backs on them (Suburban). I don't like foot peg extensions on these bikes. I put a front crash bar on mine. I think they look good and they save you from piercing the valve cover if the bike gets dumped.
1200 RT LC's are smoother, more powerful and have a ton of good electronic stuff. They don't overheat, have a built in fan that comes on for cooling in stopped traffic. I got all the goodies this time. I've never used the bike speakers but I have a bluetooth thing on my helmet. It takes some doing to figure all this out. I have a friend with one, so it was easier. Also check out bluetooth I miss the dlockable fairing boxes on all the earlier RTs. They are great for storing water and rags on the road. I could clean bugs off on interstate rides. I suppose I could carry a little bottle in one pocket and a rag in the other, but I just thought of that, so haven't tried it. Even the LC needs a new seat and windscreen if you ask me. I also got bar-baks and a front crash bar. I got Illium for both the bar-backs and crash bars and I think they're the best value out there. I have not connection with them. I've stuck with Sargent saddles. They're not perfect but you can move around on them. This is nice for cornering and for long rides when you need to get blood to all your parts. Sometimes I stand on pegs at speed to cool off or get blood moving in my legs. Sometimes I sit on the pillion seat reaching forward to the bars to stretch out hamstrings and back. Someone probably has written a book about exercises you can do on your bike while riding on interstates. Might make a good thread title?
Happy Trails!