If you want an F5 that will be a great camera. The slide question is sort of sideways related to that. The F5 meter will probably do at least as well as any camera with slides if your goal is to just point the camera at stuff and let the camera do the thinking. Of course that is what matrix metering does - tries analyze the scene like a photographer would (in ye olden days). It of course does not have the advantage of knowing exactly what the subject is, but I bet it will do a fine job. BTW, that is not really about the accuracy of the meter. Any modern meter should be accurate enough (the F80 has a great meter). This is more about the camera guessing what you are taking pictures of.

It sounds like you want the F5 anyway and I'm sure you will love it, but with any camera an incident light meter can be a great tool and a great educator for difficult situations like that. It measures the light falling on the scene instead of the light reflecting off of it. One thing you start to realize quickly is that the light often isn't changing much, even though camera meter may be moving all over the place.

Enjoy the upcoming new camera.