When I want to record 2 tracks at the same time here's what I do.
My interface is a Saffire.
So on track 1 I select saffire Left for input to the track
And on track 2 I select saffire Right for input to the track
This allows me to record 2 different mics ...each into it's own unique track in MC.
Your interface should show up in the audio options available for input. there should be a STEREO option for ONE TRACK as well as Mono Left and Mono Right options.
When recording one track I always select the mono Left option. That gives me one mic into one track. The system acts like it is totally mono which is fine for mono instruments.
I rarely use STEREO input for anything.
I don't see a need or reason to upgrade to X1 from MC unless you need the functionality of having more tracks available to record simultaneously BUT.... you will also need a different interface which can handle more than 2 tracks to accomplish that goal.
It's not that MME is so hated. It actually is a good driver when it's used for what it's intended to do which is drive a stock soundcard playing MP3's and waves in a computer as a sound card when you play games and watch videos..... It falls woefully short when we ask it to handle the massive data we necessarily run through our systems when we record...and when you throw in the softsynths that must be processed in real time.... it's kinda like trying to run the Indy 500 with a dune buggy..... it will get you around the track but not as fast as it needs to. It'll be the last one across the line every time. MME can not do the job properly. ASIO, on the other hand IS specifically designed to handle audio properly and it lets you run with the big dogs.