I also tend towards minimalism, and not having stuff just to have stuff. So why is my collection growing? Because I don't yet know what I really like.
My Dad's "51" will never ever leave my collection. It is one of the very few possessions I prize. I like its quick deployment and very fine line, and love its absolute reliability, and more than anything, its connection to my Dad, who has become my hero.
Nor will my Pelikan M200 leave my collection. It was the first bottle-fill only pen I ever bought, and it is the pen I've had longest. It is an extraordinarily good pen, and I love its girth, its light weight, and especially the lifetime free repairs. Unlike my Dad's "51", I am willing to fill it with nearly anything (except Baystate inks, "51" ink, Superchrome, and iron gall inks). My M400 will likely get kept for very much the same reasons. I bought it to see if all of Levenger's blathering about the romance and warm feel of celluloid or the wonders of a gold nib had any meaning for me. They don't.
My mandarin yellow Ahab may get sold at some point. While I love its size, light weight, and brilliant color, and deeply appreciate the line variation I can easily get, I am not in love with the need to turn the cap (or barrel) three or four times to uncap, and two or three to cap it. With the Pelikans, this operation is a single twist each time.
My copper Estie hits a lot of high notes. It's beautiful, its medium manifold nib is very smooth, and it's very light. But it also requires at least two turns to cap or uncap, and it's just a little slim for my taste. I've learned that lever fillers hold no romance for me, even if I do appreciate how easy and simple they are to fill. In fact, I've occasionally been concerned that I might damage the lever if it snags on something because I failed to notice it was slightly extended as I slip it into a pocket or pen roll. I may come to sell it.
I have a Sheaffer PFM and a TipDip Imperial that should start to see regular use fairly soon, as I have been able to afford restoration. Because they are gifts from in-laws, I am likely to keep them no matter what. They reflect how quickly I earned the appreciation, friendship, and respect of my wife's brother and mother. And they ought to be pretty darned good pens. The PFM is likely to see the same sorts of ink restrictions as the "51", because snorkels are thin and finicky, and filling and flushing the pen doesn't flush the feed or nib, and they're rare and expensive. The Imperial, like the Pelikans, will be trusted to use PR and Noodler's.
So what does that leave me wanting to fool with? Well, a vac-fill, say a TWSBI Vac 700. Will this kind of fill appeal to me? Or will the need to unscrew the blind cap a half-turn for extended writing sessions annoy and aggravate me? What about the need to unscrew the cap, instead of just pull it off?
And a volcano grey Monteverde Intima. This pen is so absolutely gorgeous and striking I can hardly stand it. While I generally prefer bottle-fill, I've been refilling Sheaffer carts in my Viewpoint calli pens for a month or two, and it hasn't bothered me. And I have a small stash of international carts that I can use and refill. And it looks like I can swap in my Ahab's nib if I so choose.
And a Parker button fill, just to see what I think. And maybe a Vacuumatic, even though I know that the diaphragms often tend to go south. And a 1.5mm Parallel. And maybe a 2.4mm Parallel. And perhaps an ebonite pen of some sort, once again to see what I think.
I like the idea of having a bunch of cheaper and/or older pens with slip caps so I can try whackloads of ink. But common sense sort of dictates that I limit myself to about 4 or 5 at a time: a writer for black, a writer for colored ink, a broad/calli pen for black, and a stub for colored ink. And maybe a Platinum Plaisir for markup ink or a Noodler's super-cheap eyedropper full of Baystate Blue.
What have I learned I don't like? Pens that are heavy, narrow, leaky, flimsy, or require a lot of screwing and unscrewing to use. I like my pens to be convenient, comfortable, and trouble-free.