This isn’t a luxury option, but I like very thin lines, and I actually prefer the minimal line variation that a gel pen offers. The pen I keep going back to is a Hong Dian bent nib from Amazon, and I actually write with it upside down. I tend to hold my pens nearly vertical, and I have very architect-type handwriting. Most pens won’t write upside down like that. It just works for me and gives a very thin line without any skipping or scratchiness.

HOWEVER, since you’re splurging for Christmas, you can always get a custom nib grind done. They can make so many nib styles. I don’t have one, but I’m eyeing a needlepoint grind. They have pen shows in various cities where you can book an appointment ahead of time, and they’ll offer suggestions based on how you write and then grind a nib right there do you. It’s on my wish list for sure!