Recommendation for a high-quality UV filter for Leica Summilux lenses?

Hey everyone! I recently finally bit the bullet and added a 50mm Summilux-M ASPH to my kit, and I’m absolutely in love with the rendering. However, I’ve found myself being a bit overly precious with it lately. Every time I’m out shooting street photography or in slightly dusty conditions, I get a hit of anxiety about a stray finger touch or a bit of grit scratching that beautiful front element. It’s a massive investment, so I’m leaning towards getting a high-quality UV filter for peace of mind, but I’m really torn on which way to go.

I’ve traditionally been someone who avoids filters because I hate the idea of putting a $100 piece of glass in front of a $4,000 lens. I’m terrified of losing that legendary micro-contrast or dealing with nasty ghosting when shooting into the light. I’ve been researching the B+W XS-Pro MRC2 Nano series, which seems to be a gold standard, and of course, there are Leica’s own UVa II filters. Some purists swear that the Leica-branded ones are the only way to ensure the color balance remains identical, while others say you’re just paying for the name.

I have a couple of specific concerns: first, I want to make sure the filter is slim enough that it doesn't cause any vignetting or interfere with the built-in lens hood on the Summilux. Second, I’ve heard some filters can actually cause a weird reflection with the sensor on digital M bodies.

For those of you who regularly shoot with Summilux glass, what is your go-to for protection? Have you noticed any real-world degradation in image quality or flare resistance with the Leica UVa II versus something like a Breakthrough Photography X4 or a Hoya HD3? I’d love to hear your recommendations on what provides the best balance of protection and optical transparency.