Mystcraft portals are a lot of fun. They also can't take you to another point within the same dimension unless you get yourself an intra-linking book, so in most cases you won't run into any recursion issues.

The mod's license is "All Rights Reserved" and as such does not allow me to support it in BP. They don't even provide any source code.

For non-trivial integrations, I'll generally only consider mods which are released under a GPLv3-compatible license (e.g. one of these).