I personally dumped this release myself using: Dreamcast (duh), BBA, SYSTEM-DISC 2, httpd-ack, Family Guy's pack, IsoBuster, HxD, Daemon Tools and last but not least the infamous Padus DiscJuggler.
As for changes to the final game I cannot say for sure but look at it this way: this build is at least 6 months before the game hit the shelves in Japan. Also there are 678 files totalling 134 Mb in this release, but 632 files at 846 Mb in the retail release. One thing is for certain: things are different!
If you use a second controller you can unlock the following debug options:
A changes the camera angle (stick rotates camera when possible) in cut scenes. In-game it brings up a save screen.
B teleports the character to a corridoor, B + direction teleports elsewhere.
X makes the character climb in mid-air (then gets stuck so you have to teleport)
Y adds a debug overlay to the screen, Start cycles through debug modes 0 to 5.
Using the L trigger changes the player character's head. Teleporting resets the head to two places off default. Warning - if you change it to the 10th/8th head it is an invalid head and the game crashes. You can tell when this happens as you have a top half with brown hair and the bottom half is deformed.
Using the analog stick and D-Pad appears to change values in the debug overlay but as for the effects, I do not know.
This is the first Bananabreak release. Bananabreak are a group of Beta owners looking to release discs anonymously so I am serving as the public face (even if it is like a slapped arse!), but if there any thanks the anonymous members deserve them too!
http://www.multiupload.com/QJ4B165PXE
Enjoy!