Not touching anything unofficial is not smart in the Case of TES III and IV. There is so much out there that works perfectly and in no way conflicts with the original (neither technically, aesthetically, nor lore-wise) that I can see no reason not to enhance the game with it. I may not be neutral, but I am specifically not talking about my own stuff here.
But specifically: I have never played without the UMP, and never experienced a problem. It's a professionally made mod.