I recently moved from an ST1300 to an RT1250RT and while I do like the RT, I'm not sure it is worth the cost and that is a completely personal opinion. The RT is more refined. The ST engine is, IMO, better. It is much smoother. The RT is lighter, nimbler and handles better. The tech is more advanced on the RT. Yes, you have the comforts of Cruise control, heated grips and seats. I love the cruise and dont think I will use the heated grips and/or seat. The RT stock seat is better than the ST stock seat, by a mile, but still not suitable for long distance riding. I can ride for a couple of hours comfortably on the RT, while the stock ST seat was uncomfortable by the end of my driveway, but to be fair, it is a long driveway... LOL. I upgraded the ST seat to a Russel seat and I will be upgrading the RT seat to a Seth Laam seat in the spring. This is a personal thing... some may find the stock RT seat fine. The RT has just as crouched a riding position as the ST, maybe worse. Keep this in mind if you have long legs. Wind protection is the same, for the most part. Fuel range is a bit less on the RT, but it doesnt seem to bother me... YMMV
In summary, the RT is a great bike but so is the ST. While the RT is more refined, I'm realizing that the ST was not that far behind to begin with. I do LOVE the lighter weight and the nimbleness and improved handling... I'm just surprised that the RT was not leaps and bounds better. You can upgrade the ST with cruise and heated grips for alot less than the cost to upgrade to an RT. I dont think you can go wrong with an RT upgrade, as long as it is worth the cost to you.