True Interlaced video with Nero Digital

I'm working with a true-interlaced video (DVB MPEG2 Streams). Every time I open a .mpg (mpeg2) file with Nero Recode, the software always recognize it as a progressive video (which is incorrect). So I need to manually select the deinterlace option. But what I would like to do is keep the video interlaced. Is that a good idea ? The bitrate of the source is about 2400 Kbps. I'm using low bitrates for Nero Digital, like 600-700 Kbps. I think if I keep the video interlaced, I would not get the same quality, using the same bitrate, right ? Anyway, what I would like to ask is how I can configure Nero Recode to handle true-interlaced video. Thanks!

Thanks for your answer. I’m very pleased with your attention. Speed is my main concern. So, I guess Nero Digital takes a competitive advantage over others codecs. And with the kind of video that I'm encoding, I think deinterlace is a reasonable option, as long it improves the video quality.

Yeah, but 50i to 50p would work fine with good deinterlacing. Has somebody tested if H.264-encoded 50p video needs twice the bitrate of 25p (or 50i with a suitable encoder), when the original source is interlaced? Of course motion in the source video has an effect on this, but it would be nice to see some examples of how efficiently modern video encoding techniques can replace interlacing altogether. Maybe I'll finally set up AviSynth on my Linux system to try this.

Ateme and Elecard are preparing their commercial H.264 codecs with interlace support. No info when it will be finished.