IME, much more flexibility to book something else, even a half hour change - they are often flexible if you get the right agent.

For refund, I believe there are set rules, and they tend not to deviate from them. Its been said here its 90 minutes or 120 minutes depending on the thread you read.

For example, my connection in CLE changed from 85 to 38 minutes - still very legal, and unlikely to refund - but they had no problem changing the flights to accommodate me.