I can't think of anything off the top of my head that would directly be impacted from loading it. It's mainly that it wants to do things its own way and if you've done them outside of it, then it will override your customized settings with its own and break things. Apache is where I've seen it do this the most...I have not tried to do it with quickbox. There are a million ways to do a specific thing in linux. QB goes about it one way and Webmin goes about it another...both will work but they might conflict if you've already done it another way and try to alter it in webmin.
I used to be a big webmin/virtualmin user back in the day but I found it just got in the way more than it helped. The one thing I do like about about it is the auto patching and email alerts on the patching. I still use that today on some of my non-production servers.
I think you're fine to install and use it..just be aware that using it to edit things could cause conflicts and break things.