I'll preface this by saying my partner and I love the ride at DCA and were actually disappointed with the DHS version when we rode it for the first time in May. (We're among those who think the Fifth Dimension room is just a waste of time.)
The DCA ride isn't "much shorter" at all. It's actually just a bit shorter than the DHS ride, and what is cut out is mostly the wasted time at the end of the ride getting to the unloading zone. The main differences at DHA are that the ride loads and unloads from a single station (there is no separate unloading zone) and uses one drop shaft instead of two. Because of this, there is no Fifth Dimension room. Instead, the elevator backs up from the station into the drop shaft as the ride begins, and then moves forward back to the station as the ride ends. There is no forward movement during the actual ride, and there is no lateral (sideways) movement at the end of the ride as the elevators return to the loading zone, either.
The tower and grounds are somewhat different, but the interior is virtually identical once you get into the hotel lobby, except that after you exit the pre-show rooms, the boiler room loading zone is two stories tall instead of just on one level. This is because DCA uses two ride vehicles in each shaft. While one is running through the ride, the other is unloading and loading.
When the doors at the loading station open, you walk across a narrow hallway to reach the actual ride vehicle. Your view down the hallways is usually obstructed by cast members standing to either side. (This is the hallway used as an exit path at the end of the ride.)
When the doors close, the lights go down and the elevator moves slowly back revealing a starfield where the loading zone was while you hear a "Rod Serling" narration.
The elevator then suddenly rises to the second floor, which is not part of the DHS ride. The doors open to reveal a mirror image of the riders in the elevator which begins to morph until the riders are ghosts as the narrator tells the riders to wave goodbye.
Then the elevator rises to the third floor which essentially is the same as the second floor at DHS. This is the floor that tells and shows the story of the guests getting into the elevator and the tower getting hit by lightning. Instead of the elevator moving forward into a Fifth Dimension room at this point, anticipation is created for the drop sequence by showing the ghostly guests in their elevator surrounded by a starfield like the one you see as the ride begins. Their elevator shakes and then suddenly drops away. The narrator tells you it's now your turn, and while the doors to the third-floor scene are still open, the ride vehicle suddenly falls and the drop sequence begins.
The drop sequence is always the same (there is no randomization at DCA), and the view to the outside, over the park, is somewhat less obstructed and easier to see than at DHS. There is also less light bleed-in, so the lower portions of the drop are darker than at DHS.
As the drop sequence ends and the elevator finishes its final plunge, a crashing sound is heard that sounds like pieces of metal smashing and hitting the ground. It's a really effective, fun sound, and is absent at DHS.
At this point, you're back on the level where you started, and the starfield reappears as the elevator moves forward back to the station as the closing "Rod Serling" narration plays. When the doors open, you exit through the hallway that sits between the loading station and the elevator while the actual loading station doors remain closed. Just like at DHS, you exit through a gift shop where you can purchase your ride photo.
My partner and I really like the pacing on this version of the ride. Watching the ghost elevator fall, knowing you'll be next, really creates a sense of tension. In Orlando, we expect similar tension from the Fifth Dimension room, but just found it to be silly, with old 1990s projection technology and so much light that you can easily see ride mechanicals. We did like the "dimensional rift" that opens up right before the drop sequence begins, but we didn't think it created much tension, either. We also thought all the twisting and turning the elevator does at the bottom with the lights on while you travel to the unloading zone took away from the magic, as well.
Your elevator mileage may vary
You can see a
typical POV on YouTube here.
I'm sure I would still love the ride. Another thing I wondered about was since you don't move through the building before the drop, does that mean you don't hear Rod Serling's haunting voice right before the drop as well? Or is that still there? 
