-1 at this point in time.
Let's be honest: mining spawners is really cool. And it's a great incentive for Elite+. But it was one of the reasons that the economy was so bad... and I don't really think anyone wants another Meep Reset.
Now, what would be really cool is if there was some sort of plugin that enabled spawners to have "health"... and maybe one could repair a spawner by sinking 500k into it or something. That could offset the economy a bit. At that point, the MeepStaff could probably consider re-enabling Silk Spawners. But until then... it's probably not a good idea to tempt ourselves. Besides, it seems like people are doing pretty well with vanilla grinders (*cough* *cough* @L0ST_CL3R1C )