is there a way to use the mod but not change Alyx at all...
Yes. When you install the mod, the entire thing is standalone. There is a configurator that looks like this:
From here you can enable/disable effects to your heart's content, including the music, weapon, and bloom changes, to name a few. You also get a "Character Pimper" which contains most of FAKEFACTORY's previous and current versions of Characters as well as the originals. And for Alyx, you can even change them up between chapters.
The creator of this mod gets a lot of hate, and it's been that way since the first version came out 9-ish years ago. You may hate him because he wants to make Half-Life fit his own vision, but he's been modding for all this time in spite of that. I have some mad respect for someone who can continue to share with a community who despises them, especially when most developers, indie or otherwise can't handle criticism these days.
Is there a way to use the mod but still have it look like you're not using the mod at all? =)
I'm kidding. I don't like it, but it's mostly because of the bloom.
That can be changed or even disabled. Most of the mod can be disabled. I appreciate that you don't like the mod. What irks me is when people try to spread their disdain for something to those around them. Let me be me, and you be you, and all that. And I'll be posting HL2, and Cinematic Mod shots for a long time to come, considering I replay them both multiple times a year.