Right now I'm running an i5-2500k Sandy bridge that is overclocked to 4.8ghz. At this moment, I have the uportunity to get an i7-3770 ivy bridge, do not know if I would notice improvements. Seems the Ivy bridge can not overclocked to an high level but according some test the Ivy bridge can handle single core applications better.
Does Woff have any benifit from HT or should I stay to the i5-2500k.

If you are trading off lower Mhz for higher single core efficiency, I'm not sure you will see much of an improvement, to be honest. I don't think WOFF benefits from hyper threading at all.

CFS3 uses just one core, the only benefits multiple cores have is that they handle all the other "stuff" going on in the background while you are playing WOFF.

You want the fastest core possible to play WOFF, and at 4.8GHz, you will not improve any with a slower CPU.

Thanks think it maybe better to wait for the Kabylake i5-7xxxK and the new highend AMD Vcard, for real power.

I had the same thought, dutch, as my rig is getting long in the tooth, but as you said the 3770 can't be overclocked as well. But the fact that you got 4.8 GHz out of your processor give me hope! I may try for a little more speed on my I7-2600K now!