I've said it elsewhere, but it's worth repeating. Sprint *never* had a 30 second recast for 20 seconds of sprint in combat (it was 51 seconds; explanation forthcoming). To change it to that would allow considerably more sprinting than prior to 4.0. I'm not sure that's necessarily a problem, but it has to be kept in mind.

The reason for this, in case it's not clear, is that Sprint's duration was based on your current TP: 2 seconds per 100 TP. Outside of combat, you gain 100 TP per tick (3 seconds), so you get back 1000 TP in the 30 seconds of Sprint's recast. However, during combat your TP regeneration rate is only 60 TP per tick, so in 30 seconds you'd have regained 600 TP, which would only give 12 seconds of Sprint duration. You wouldn't be back to 1000 TP, even as a mage, for 51 seconds. That's actually not that far off from 60 seconds, though obviously it's still a nerf. But this isn't nearly as extreme, in combat, as people are making it out to be. (Gatherers are another story.)