I think we should start using IGTs for 100 Mario Challenge runs alongside RTA since internet speeds can affect the time. Using IGTs would allow for a more accurate measurement of runs.

IGT has its own issues with it only being done to the second, and levels with doors or tubes would have an advantage

Actually, it might seem controversial. Here's my 2 cents:

IGT wouldn't be a bad idea because after completing the level, it shows how long it took you to do it. IGT also translates perfectly to IRT (this is the only main series Mario game ever made to do that) and it does it to the thousandths place of a decimal when it comes to seconds.

EWaller brings up a good point though, and he seems to bring this specific argument in every Mario game when somebody seems to want to move over to IGT, especially when doing IL's, is that time freezes when going through doors and pipes.

If you're doing 100 man's though, you should already have good enough internet where the loading times are all the same as another person with a different ISP.