If you playtest the summoner or the witch and come to beleive it is overpowered or underpowered its a good idea to post the build and say what happened during the encounter in detail. Saying it wrecked an encounter or it was useless will probably not convince anyone of anything one way or the other. It will also give the other DM's and players a chance to know what to expect.
Poster will also want to be sure you did not make any mathematical errors with the eidolon.
I probably wont get to test the summoner, but I might get to test the with in a few weeks. I wish I was DM'ing this weekend. It will be in an NPC boss type role. I will post the results here.
PS: If you have any houserules that affected combat that should be noted also.