I've performed some tests with a couple of trimmers to see what they've changed/removed in the original files.
I did this with Total Commanders "compare files" command, so anyone who uses TC can test it themselfs.
Just remember to click the "binary" checkbox before you start comparing.
Remember I only tested it with
3 clean roms, and 4 different trimmers, so don't sue me if Download Play doesn't work for you. Thanks.
ROMS:
0080 - Nanostray (U) (Lube).nds
0434 - New Super Mario Bros (U) (pSyDS).nds
0595 - Clubhouse Games (U) (WRG).nds
TRIMMERS:
R4DS ROM Trimmer 1.0 (sorry found no link)
R4DS ROM Trimmer 2.0 (
link)
SkinnyRom v1.2 (
link)
NDS Tokyo Trim v0.42 (
link)
CONCLUSION:
R4DS ROM Trimmer v1.0 doesn't work. It removes a lot though, and the ROM's sizes becomes the smallest. (Probably because it removes TOO MUCH! So don't use it.)
R4DS ROM Trimmer v2.0 works fine. It removes the crap from the ROMS without destroying them. But no batch trimming can be a pain, so I wouldn't recommend it unless you were just going to trim a single ROM.
SkinnyRom v1.2 also works fine. The batch trimming is nice and the fact that it leaves a few bytes for safety seems good to me at least.
NDS Tokyo Trim v0.42 also works just fine. The batch trimming seems a bit faster than SkinnyROM's, but that might just be me. No safe trimming is used, which probably isn't a big deal... unless you're paranoid about your ROMS not working because of it.
LONG STORY (post) SHORT: (read if you're in a hurry!)
The stuff that gets removed with R4DS ROM Trimmer 2.0, SkinnyROM v1.2, and NDS Tokyo Trim v0.42 are exactly the same.
The only thing that is different is the amount of "safe trimming" left at the end. With R4DS ROM Trimmer v2.0 leaving the most, followed by SkinnyRom v1.2, and last NDS Tokyo Trim v0.42 which leaves none.
So, I hope that clears up a few answers about which rom trimmers work and not.
I can test a few more if you like... just give me a link, AND have some patience.
EDIT:
The settings I used for SkinnyRom v1.2 was:
Safe Trim On and Off. Byte jump size 128.
UPDATE:
M3 ROM Trimmer v2.0 trims EXACTLY the same as
R4DS ROM Trimmer v2.0.
(Produces identical files.) No surprise there.