[Edi]

I have never had any problems calling specific sites by number, either with #knownfeature or #feature. However, if you have a lot of #knownfeature commands (as in if you try to put all sites into a map using #knownfeature) it craps out somewhere after 500 sites, but I don't remember exactly where. A little bit before Merman village, I think. If you change half the #knownfeature commands to #feature, there will be no problem.