It will be a great difference. But the power and the accessories will take you to the next level. I myself came from a FXDX, but never felt sorry for taking that decision.
My last Harley was my first one. It was a 2008 Rocker C. Damn it was a sharp looking bike. I added about 4k in chrome wheels, etc. I rode it from Nashville to Myrtle Beach Bike Week once. It was not that kind of bike and my wife and I wanted to move up to something we could enjoy together with more comfort & luxury (like a stereo). I am not putting any money into cosmetics. All extra money is going into comfort & conveniences (and a little extra power). Check it out...
Had a 2006 Suzuki C50T, 805cc, buzzed the handlebars so bad at highway speeds above 60 it would make your hands fall asleep. Ran around 5000rpm at 70mph, 3000rpm at just under 50. And the pegs were so far back my wife's legs cramped up and had to pull her off it when we got home. Love the low rpm cruising and stretched out feel.
Before my 11 Street Glide I had an 08 M109r,08 cbr600rr,09 gsxr600 and a 09 Spyder. Not all at the same time. Lol. I think I finally found a home with my SG.
My last bike was an HD VROD nightrod special....before that it was 2 separate CBR 1000's and 2 600's. Before that was my first street legal bike which was a Kawasaki Vulcan 750.
Started off with a 72 Honda cb 100 I believe, then went off road for years preferred the sand and dirt over asphalt, got my first Harley last year 2014 low rider put 1700 miles on it then couldn't wait had to pull the trigger on the new sgs since that's what I really wanted.
2009 Vstar 950T to 2014 SGS. In five years only rode 2500 miles on the Yamaha. Not one year yet on the SGS and have gone over 3000. Not hard to tell which is more fun!
Coming from a line of sport bikes but the most recent was my 2012 BMW S1000RR. Went from 194hp to the wheel and doing speeds of 186+ to my 2014 Street Glide Special in Denim Black....Took a long cold winter to come to senses and realize that my life was more important than the adrenaline rush I got my S1000RR so I calmed down and bought a Street Glide. I thought sport bikes cost a lot to modify, HOLY COW, HD should stand for Hundred Dollar haha can't buy anything besides my antenna rubber plug for less than $100 haha. Cheers!