Help Question about ditching Sprint hotspot and using a free hotspot app in its place

[mwg]

So I've been using the Sprint hotspot app for the last couple months, since shortly after purchasing my Evo. I haven't rooted my phone yet, out of concern for data loss, voiding the warranty, etc. If I do root the phone, and then use a free hotspot app (by the way, does anyone have any recommendations for a good free hotspot app?), then, after canceling the hotspot feature, (1) can Sprint detect that I am using the phone as a hotspot for free, and (2) can they do anything about it (I *think* that the contract mentions something about not using the phone as a tether for other devices without paying for the hotspot feature)?