I went from a Sportster to the FLHT. Within a few hundred miles you will be tossing the Tour Bike around like a Sporty! The size and weight are not as big an issue as most think. On the Highway the size and weight are your friends.

 

My back sucks too. Road a Sporty for 15 years. I've been on an Electra Glide Classic for the past 9 years. I have lower back pain. The touring bike is the way to go.

If you can, try to get a seat with the back support pad. It helps me a lot.
Like wood butcher said, people seem to freak out over a big bike. Don't even worry about it. The touring bikes ride like a nimble dream.

I went from an 85 Sportster to a 2000 Dresser. I'm only 5'5". I thought oh crap I'll never be able to ride this thing............I was so wrong.

Get the dresser you won't be sorry. Don't forget to stretch your back!

 

SG 1
I had been wearing a modular DOT. I suffer from degenerating discs between C4, C5 and C6. I would have a burning in my neck that shot down my arms and out the ends of my fingertips. I switched to a 3/4 open face HJC CL-33 open face with an opticly correct face shield. The modular weighed in at 5 lbs. The CL-33 is just over 2 lbs. No more burning. Also are your arms straight out to the bars or are the elbows bent? I notice that your scoot has a short windshield. Any buffeting coming at you will transfer that vibration to the discs in your neck and along with arm position will cause the burning. My scoot has the OEM windshield and along with my face shield I have no wind problems at all. I am a short rider at 5'4" and that helps keep be behind the windshield.

 

FLHR would probably be a lot more comfortable ride-factor for you. My OL has several bad discs and she's fine, as a passenger anyway, on mine.

As the rider (driver) though, might need to go to taller bars for even more comfort. I have an '07 so controls are a little different from an '09 but FWIW, my 6'2" grip position was WAY too low with stock bars on the '07 Road King.

 

I just traded my 2005 FXDI for a 2009 FLHX. I had my Dyna set up with forward controls, a mustache bar, Corbin Dual Tour seat and a HD windshield. I put 45000 miles on it in four year and found it very comfortable. I could easliy ride 400-500 miles in a day sometimes as high as 700. The Dyna is a wonderful all around bike. The one place it didn't excel was on the interstate. It did ok but it seemed to run a little hard at 70 mph (5 speed trans).

The FLHX is a great. I am not sure but I think it may handle better than my Dyna. I love the radio and the fairing seems to help on those chilly mornings. I like the floorboards but miss my forward controls and the factory seat has to be the worst seat I have ever been on. The FLHX takes quite a bit more strength to backup into a parking spot though.

I am very happy with the FLHX and I think once I get a better seat and add a set of highway pegs the FLHX will be amazing. However if you are not planning too many 600 mile days in the saddle I think a Dyna set up with a good seat, fwd controls, a windshield and a six speed trans can be a very comfortable bike too.

 

I am having a bad back. I had a Lowrider, but testdrove a Street Glide and immediately putted the Dyna for sale. I recommend a tourer for you.

 

Get the Ultra, best of all worlds.

 

Touring is the answer for back problems, the Streetglide it a bit stiff (2 inch rear suspension) the ultra is the caddy of comfort, but you may have to change bars so you don't lean forward.. I have a Streetglide and changed the bars to "reach bars" and now I'm good to go... I also have back problems and every time I see a crotch rocket I wench in pain. Isn't Youth Deceptive...

 

A touring bike with a riders backrest and I can ride 500 miles in a day with out backpain.

 

Speaking from someone thats had back surgery and open heart surgery and had a softail, Id say go with a FLTR. The frame mounted fairing will take away the wind beating on your arm and shoulders, which radiate down your neck and back.