When it comes to the Cutie Mark Crusaders, I think 'Sisterly Hooves Social' would actually be one of my favorite episodes that centers around one or more of them because it wasn't just focused on one or more of them looking for their Cutie Mark. So, I would have to agree. The CMC trying to find their Cutie Marks is cute, but I don't want them going at it for so long in which it because repetitive and redundant. It's like what was said above: one could only learn so many lessons about being patient and simply waiting for someone to come.
With that said, this episode was alright. It was a good episode, but I it didn't still show anything special. Like what was mentioned before; this episode could possibly have been skipped, and everything would be alright because there wasn't much character development. Of course, this episode did give us a new really nice background Pony, so everything has it's good sides, I suppose.
As for the new episode rumor, it sounds interesting. Spike seems to be a bit underrated when it comes to popularity, so it's nice seeing him get some scrteentime. I'm sure plenty of people are still waiting for their AJ, Fluttershy, and Pinkie episodes. In fact, Fluttershy hasn't shown up in the last two, and she didn't get much screentime in the Luna episode. I think out of the three who we haven't heard an episode for yet, AJ has gotten the most screentime. Especially in these past two episodes.