If you keep within spec you're covered by warranty. Which I never needed even with heavily oced CPUs on air going for years.
The power draw of Ivy Bridge is lower than previous generation and the performance is slightly higher. Job well done.
Cooling will become a concern in the future because TJun cannot be raised indefinitely, but if it works, why fix it?
Good cooling keeps the component temperature within spec. Efficient cooling can do it silently. If you don't have to cool your CPU to an artificially low 70 deg cent. Ivy Bridge is easier to cool (keep in spec and even silently) than Sandy Bridge.
If you were about to buy a new Desktop / HTPC, would the motherboard Asus P8Z77-V PRO,
and a Intel core I5 2500K 3300mhz be a wise choice?
Get the 3570K.
Sandy Bridge is only for hardcore overclocking. It might be easier to reach 5GHz with Sandy Bridge. Ivy Bridge is a little more efficient so 4.7-4.8GHz is roughly the same as 5GHz Sandy, only it's below 5GHz. If that MHz number is somehow magical to you, you need Sandy Bridge
Intelligent people use new efficient tech within spec and smile because it makes life easier.