I use it all the time in emulators, and just like Assassinator it is one of the reasons that in some cases I prefer emulation over that actual console.  I think it definitely is cheating, but only to the same extent that using a guide or maybe a glitch would be.  I use guides all the time and occasionally use glitches if they don't cheapen the experience too much.  If someone thinks they are cheats then they don't need to use them, and if anyone calls themselves a purist then they shoudn't even be using an emulator in the first place.