I'm still alive, and coincidentally became interested in playing Sins again like 2 days before the DLC came out. Anyway I do actually like the DLC, it adds some depth to planet development that was not there before. The values listed for population figures do not seem to be accurate though, I was very excited to get my homeworld close to 1k population, though at full social specialization it was more like 700, despite what the tooltip said.
The new planet types aren't all that interesting, although they definitely do spice things up a bit. I don't possibly see how they could make the game slower, though, considering the planets they are most likely to spawn in place of are asteroids and dwarf planets. I think it'll also be interesting to see how players decide to use the different planet specializations with different factions. I.E. a TEC player with Industrial Juggernaut and a full industry specced ferrous planet or Advent with full social spec planets.