Fuel pump and rider heat have been an issues on the ST1300. But the ST1300 overall is very reliable. 13 Requires premium fuel, 11 can use regular.
Have you ridden the ST1300 yet ? The ST1100 is certainly not as fast, but I have heard some ST1300 riders that were formally ST1100 riders that actually prefer the ST1100.
See this article ;
Comparison
Quote from ADV Rider Forum : Originally Posted by Kentucky
" After owning two ST1100's and longing to own a 13 I finally bought one. It is a great bike. If I lived in the mountains of North Carolina, North Georgia or any other twisties area, it would likely be my choice. I sold the 13 after 4k miles and bought an 01 ST1100 two weeks ago. The ST is far superior as an Interstate tool for my tastes. Better aero (never could get the w/s aero sorted out on the 13), almost no heat issues, smoother throttle response and rock solid on the slab. The 13 moved around with the slightest bit of dirty air. I liked the 1300 but I love the 11.
It is really strange to say that the 1300 has more power, slightly lighter weight, better braking and crisper handling but the 1100 is a better motorcycle. Interesting. It reminds me of some of the comments I hear comparing the R1150GS to the R1200GS. " Barry
Also, there are plenty of used parts on EBay for the 1100. I bought a spare starter ( $30) and spare ignition module ( $25 ). If the fuel pump goes out, you can replace it with a LOW pressure auto fuel pump for about $40.
I've been thinking of replacing my ST1100 with a ST1300 , but I'll be keeping my ST1100 for awhile. It's in great mechanical condition and I'm happy with it, and wonder how much I would be gaining . With 76K miles, it's still a low mileage bike. They are good for at least 250K miles.