I did Mario's Theme myself, and I always try and loop as early as possible.
I also did "March Ahead".
Here's the comparisons of my loops compared to your loops:
March Ahead -
Mine = 329,728 - 1,292,311
Yours = 329,728 - 2,254,637
Wait... why does yours loop at 51 seconds? Did I fall into that trap where the seemingly second loop is actually different? Or did you accidentally loop it twice? My loop is 29 seconds.
As for the rest of them:
Battle Fanfare
Mine = 100,352 - 1,328,147
Yours = 100,352 - 1,328,744 (yours is 597 samples longer)
Goomba Village Theme
Mine = 0 - 1,588,304
Yours = 0 - 1,588,509 (yours is 205 samples longer)
Hey you!
Mine = 129,024 - 1,102,567 (in fact I only uploaded this on January 31 this year :D)
Yours = 143,360 - 1,485,679 (yours is 368,776 samples longer?)
I'm too lazy to go through all of them but... yeah.
I'm confused how Hey You! is a whole 368,776 samples longer.
EDIT: Mine is 32006 Hz, that's why ... I used the USF....