So, after this disaster of a thread, I think the ST community deserves a clean, concise post detailing all the known (and real!) differences between arcade and Dreamcast ST.
Anyway, here are the known differences:
The size of the screen is slightly off (it’s a little too narrow), making the character sizes appear to be slightly too thin. There is no evidence to show that this affects gameplay in any way.
The Dreamcast version occasionally suffers from 1 frame of input lag (possibly more if you’re using a PSX->DC controller converter), though this is undetectable by most players.
During “Round 1/2/3, FIGHT!”, the game suffers from noticeable slowdown, regardless of the speed setting. In the arcade version, if you start counting from the moment the background becomes visible until the moment your can control your characters, the elapsed time is almost exactly two seconds. In the Dreamcast version, it’s almost exactly 3 seconds. This means you must slightly alter the timing of your opening attack.
In the arcade version, O.Chun can not control the strength of her reversal fireball. (The game “stores” the strength that you previously did.) This was corrected in the Dreamcast version. Strangely, T.Hawk and O.Dictator suffer from the same problem with reversal uppercut and reversal Devil’s Reverse, respectively - there is a DIP switch to correct O.Dictator’s, but T.Hawk’s remains in tact.
Holds (such as Yoga Noogie, Boxer’s throw, etc) will always have the same duration if you don’t mash.
Almost no difference in speed between stages.
Instead of “PUSH START”, it says “PRESS START”.
Difficult to kill and dizzy at the same time using Honda’s command throw.
Guile makes a grunt when he does his kick air throw.
No hit noise during Hawk’s Fierce punch throw.
Hawk’s Jab and Strong 360 sounds don’t get cut off.
Fei Long can’t cancel rapid fire st.Jabs into jump.
O.Dictator’s st.Fierce graphic glitch is corrected.
By default, there are a few other slight gameplay differences as well (such as Dhalsim/Ken/Sagat being able to reversal super), but aside from the above mentioned reversal glitches for Chun and Hawk, all of the tested and known differences can be corrected using the in-game DIP switches.
In case anyone is interested in the timings I recorded in regards to the “Round 1/2/3, FIGHT” delay, here’s what I found. I would also be happy to upload the AVI’s if anyone wants to double-check my work (warning: it is thoroughly boring). Times listed are in the format [WHOLE SECONDS]:[SIXTIETHS OF A SECOND], so 1:30 = one second, 30/60ths of a second = 1.5 seconds.
arcade, Guile Stage, Turbo 1, Ryu vs. Ken, 2:04
DC, Guile stage, Turbo 1, Ryu vs. Ken, 3:06
arcade, Cammy stage, Turbo 2, Ryu vs. Ken, 2:05
DC, Cammy stage, Turbo 2, Ryu vs. Ken, 3:08
arcade, Ryu stage, Turbo 3, Ryu vs. Ken, 2:00
DC, Ryu stage, Turbo 3, Ryu vs. Ken, 3:08
As a comparison for how other consoles stack up as far as resolutions go, the PS1 version is too big, CCC2 is way too small, and AE is just slightly too thin. The Dreamcast version’s resolution isn’t 100% perfect, but it’s pretty darn close, and a hell of a lot better than CCC2.
Not so ninja edit
I asked NKI to combine all of them into 1 easy to read image.
James123 - For the “Round 1/2/3, FIGHT” test, I started counting frames when the background first became visible (it fades in from black), and I stopped counting once the characters could move. In the arcade version, on Ryu’s stage, on Turbo 3, Ryu vs. Ken, it took exactly 2 seconds. On the Dreamcast version, exact same scenario, it took slightly more than 3 seconds.