As Mike said, the Sprint S4 roots just fine. Use this guy's tutorials to root update MF9, install recovery, and unlock the native hotspot in about 10 minutes total: http://forum.xda-developers.com/showthread.php?t=2257101
Word of advice though. When you get the S4, don't even log into the phone yet. Skip setup, let it install the MF9 update and any others, then factory reset and do the setup. Some Best Buy stores will install the update before you leave using their WiFi. This will prevent most of the out of the box software issues.
Samsung Galaxy S® 4 MJA Rooted with CF Auto-Root Tutorial
HTC EVO Design 4G™ v4.0.3 Bootloader Unlocked & Rooted with HTC SuperTool v3
If it ain't broke, use a sledge hammer.