Depends on the metering cell. Two drawbacks to CdS meters that were never mentioned (as far as I remember) was that they had a memory - they couldn't adjust instananeously between the dazzing outdoors and the dark indoors, and needed a little time to adjust - and that they were over sensitive to red. Filter through a CdS meter by all means, but be prepared to be a stop under if the filter is red. Silicon Blue cells don't have this problem so far as I know.
The other thing to bear in mind is that filter factors are there to compensate for light lost, and a red filter will stop a greater proportion of the light if you're shooting outdoors out of direct sunlight (blue illumination from the sky) compared to indoors with yellow tungsten lights. Hence factors might be engraved on the filter, but aren't engraved in stone