Congrats and welcome to the future.
One thing I did not see in the OP is the sound card you are using. Please clarify that.
I too made a jump from CWP8 which used the internal sound card synth (GM) to MC4 and what a huge difference. I finally found the home studio solution I was seeking.
In a nut shell, my system consists of a custom computer (I used a stock laptop for 4 years with MC4) and a Focusrite Saffire interface for a sound card. My custom build computer does not have a sound card except for the Saffire.
I connect my midi keyboard to the Saffire and also mic straight in to the Saffire. No mixer, no preamps, because the Saffire has phantom power and nice crystal clean preamps. My guitar is either mic'd with my Rode condenser on the speaker or I use a POD2 straight into the Saffire as well. That is essentially my studio..... computer, interface, mic, and POD.
Everything else is "in the box".
With the advent of faster computers came all sorts of plugins for FX and VST instruments, that there is really no need to have racks full of expensive analog gear any more.
Once I got my system up and running on the laptop at the very beginning, I listed ALL my mixers, tape recorders, outboard gear (reverbs, compressors, etc) and a Korg D-16 digital recorded for sale on Ebay. I never looked back nor regretted selling any of it.
I think a few here actually use a small Behringer mixer in the fashion that you do. The important part is ... does it work and do the job you need it to do? If so, rock on. My system is more of a straight line.... form the gear to the DAW.... and the Saffire has outputs for my monitors.... so, while extremely simple and humble looking, it does the job I ask of it.
Welcome to the future..... be sure to be a part of this forum and post your music in the Songs forum. Probably the best place to learn how to improve your skills.