I looked at it from a balance reason, and here's the compairison.
Extended Vigor (2nd level spell) heals 1 HP for 26-30 rounds, healing 26-30 HP, and requires a feat (Granted, Extend Spell is usefull beyond this)
Cure Serious Wounds heals 2d8+3-10, so average 12-19, max 19-26, and that's before a feat. At 3rd level, Vigor is much more powerful, but it's not imediate (taking almost 3 minutes to run it's course). Doesn't seem too bad to me.
But I'll bow to the FAQ if that's what people prefer. There was a heated thread in the rules forum about it though.