It's not necessarily that i'm more proficient in the 300's range (old engine), it's more of the fact that the new engine requires map data.
If I don't have the map data for an area, it causes the client to crash. The only way to get map data is to get it from runescape themselves (sniff it, record it, enjoy it). Unless I use a revision that's out now, and I seriously get a high level account that will get banned 5 days after, it won't happen. Oh, and I'd have to walk through every single map area in order to get the complete world.
Many private servers only have certain areas, simply because the map data isn't available