Grief, sorry to spam the thread, but here's what I did:
Batman: Arkham Asylum Regular GFWL Edition to
New Batman:Arkham Asylum Steamworks
- grab <profilename>save0.sgd
- go to position 0x0184 (that's the fifth place in the 25th line of your hex editor. There's a place that tells which position you are. Figure it out, it's not hard)
- delete everything prior to that location
- overwrite the save (you made a backup first, right?)
- remove <profilename> from the save file, if you have it.
- open the game once, start a new game on the save slot where your game was saved in
- make sure the game saves at least once
- quit the game
- open C:\Program Files (x86)\Steam\userdata\<userid>\35140\
- delete remotecache.vdf
- enter C:\Program Files (x86)\Steam\userdata\<userid>\35140\remote
- start the game and STOP on the loader. Do not click START GAME on the loader.
- overwrite save0.gsd with your hexedited save file from before
- start the game
Batman: Arkham City Regular GFWL Edition to
New Batman:Arkham City Steamworks
- grab <profilename>save0.sgd
- open in a hex editor and HEX Search for 00:00:0E:00
- delete everything prior to the only search hit
- overwrite the save (you made a backup first, right?)
- remove <profilename> from the save if you have it
- open the game once, start a new game on the save slot where your game was saved in
- make sure the game saves at least once
- quit the game
- open C:\Program Files (x86)\Steam\userdata\<userid>\200260\
- delete remotecache.vdf
- enter C:\Program Files (x86)\Steam\userdata\<userid>\200260\remote
- start the game and STOP on the loader. Do not click START GAME on the loader.
- overwrite save0.gsd with your hexedited save file from before
- start the game
Underlined step is to go around the cloud save sync that steam does. If you overwrite the save file before opening the game, Steam will just pull whatever was in the cloud (sometimes) and fuck it all up.
Italics Is the only different step from each game.
It's a more complex step-by-step, but I suck at explaining things in a concise manner.
Edit: Fixed the folders