Hi Filip,
Greetings from Mechelen, not so far from you. There not so much Belgium HT people on this forum and even less with the HT300.
About your question : The remote interface was introduced with the HT200 and is giving you a lot of extra connection-possibilities. It's a box with all the connections that you place near your audio- and video sources and a 10 meter long cable to connect this box with your projector.
The cable itself is not a digital cable.
Pictures of the box and the cable, you can find on the website
www.kinozuhause.de/prd_remote.html
For me this is an ideal solution if you have to connect your projector with your video-sources and you need 10 meter cables (or almost). If you need to connect them (component, s-video,composite, computer) and you use quality cable, the RI will cost you less and you have, as a plus, twice as much connectors (2 x s-video, 2 x component...).
If you buy the RI together with your projector, you get a better price, then when you buy it separately. (at least with my distributor)
So, I hope this helps. I've recently read some other treads in this forum about the remote interface, if you do a search, you certainly will find it.
Greetings from Belgium,
Marc Bosmans
www.adynco.com (HomeCinema Center)