Wow, I totally missed page 2 of this thread.
Yeah, I still have to go with my previous statement that you (IMO) do not need to go to an external mixer for your mics. Also, you can use 1/4" on Mic 1 as well, there is a connector in the middle of where you plug the XLR cord in. I don't have nearly as good of a mic as you do (I have a Shure something... not even sposed to be used as a main mic lol) and I have had absolutely zero issues. If you are worried about it, can you do a mock setup somewhere (basement, garage, etc) and talk on the mic? Remember that POST button really helps too. If you are getting feedback from the monitors (I havent had an issue yet), you can always turn yourself off in the monitors.