Are all Omega stages the same length?

Edit: With the release of SSB4 for WiiU I must mention that the following data was collected from the 3DS version of the game. If needed I'll update, but I'm unsure if the person asking is even interested in one.

Firstly, not all Omega stages are exactly like FD in design, since FD also implies a traversable bottom part which can be used by characters like Jigglypuff and Kirby. Magicant Ω, Spirit Train Ω, and Rainbow Road Ω are examples of stages that are FD-ish in design, in fact, only Battlefield, FD, and Flat Zone 2 have pronounced bottoms.

A lot of Ω have a wall right down to the bottom blast line, though, which can be useful for certain characters that can wallcling, unlike FD. These vary in size and shapes from my personal perspective, the most notable being Arena Ferox Ω's wine glass shape, but I haven't thought up of a method to measure these accurately.

However I've personally measured the surface distances (which is what I assume your question is about) in Training Mode, by using Greninja's back crouch movement and moving from the left edge to the right, on 1/4x speed.

The following is a list of the times it takes to traverse each stage, give or take a few ms of error because of multitasking with the timer. All stages are Ω, all times are in seconds:

• Paper Mario: 23.276
• WarioWare, Inc.: 23.295
• Flat Zone 2: 23.316
• Reset Bomb Forest: 23.438
• Spirit Train: 23.442
• Prism Tower: 23.456
• 3D Land: 23.457
• Arena Ferox: 23.473
• Mushroomy Kingdom: 23.49
• Jungle Japes: 23.538
• PAC-MAZE: 23.563
• Wily Castle: 23.581
• Green Hill Zone: 23.639
• Tomodachi Life: 23.662
• Mute City: 23.682
• Living Room: 23.686
• Final Destination: 23.698
• Tortimer Island: 23.703
• Gerudo Valley: 23.709
• Distant Planet: 23.712
• Find Mii: 23.718
• Golden Plains: 23.728
• Balloon Fight: 23.735
• Yoshi's Island: 23.763
• Magicant: 23.765
• Dream Land: 23.771
• PictoChat 2: 23.775
• Boxing Ring: 23.776
• Battlefield: 23.846
• Gaur Plain: 23.849
• Brinstar: 23.854
• Corneria: 23.881
• Unova Pokémon League: 23.883
• Rainbow Road: 23.962

So I want to conclude that it is a camera illusion that makes stages look bigger than they seem. PAC-MAZE, for example, seemed to zoom in differently than WarioWare, Inc.'s.