It shouldn't make any difference. 480i to 480p conversion is just deinterlacing (combining the interlaced fields into a progressive frame) so it won't introduce any artifacts into the image.
If the TV gets 480i, then it will have to deinterlace and then scale to 1080p but then again it may scale to 1080i first and then deinterlace to 1080p. Having the DVD player do the deinterlacing is just saving the TV a step.
I just pass everything through to the TV at its native resolution and let the TV do deinterlacing and/or scaling however it chooses.