The big difference is that RRDNS contains all of our business logic to enable things like Orange clouding, and other DNS based features. Those depend a lot on how our infrastructure works, and are not useful to others. It's also a much older codebase (it probably started before 1.4?) and therefore goes out of its way to avoid putting pressure on the GC and had other funny bits in it. Finally, RRDNS has seen a lot of abuse and by now is pretty well hardened :)