Some processors output a reset on the reset "input" when the watchdog bites (beware this information is usually buried deep in the datasheet), with such a device you need open drain, for those where reset is an input only it does not matter.

Well, thanx Erik! Very useful information. I 've read the datasheet and the manual (the chapter about resets of the FX2 uC) and it is clear that the /Reset pin of the FX2 functions only as an input. Also, as I have already stated, FX2 doesn't implement a watchdog timer, so there is no case for the /Reset pin to function as an output as well as an input. The same stand for my DSP mp3 codec (Micronas MAS3587F) and for the PSDs flash memories. So I believe that a reset/supervisory chip with a push-pull /reset output would be the one suitable for my case.

From the search I have done in Maxim's site, I think that MAX6746-MAX6753 product family is a very good solution, not only for my project...

As you see Steve, I am convinced to use a reset/supervisory chip :)