Just a quick update:
I went to my local art supply store today and got this, the Pentel GraphGear 500 with 0.5mm lead. (I deliberately went to the architecture/drafting section, where they sell all the weird rulers, figuring there I would be among my people.) It's pretty nice. It made suffering through the rest of my Biostats problem set a relative pleasure. (I shouldn't overstate things. I finished the problem set. Period.) The pencil feels good (despite having a non-padded metal grip), the balance is satisfying, and the eraser and lead are of nice quality. I would have preferred a metal body (while the weight is overall substantial, only grip and tip are metal, while the body itself is made of plastic), we can't always have everything we want, at least not in this price range. Or, I guess I could spring for the Pentel GraphGear 1000, which has an aluminum body through and through, and must be nicer if for no other reason than 1000 is twice as much as 500, right? MATH.
If I'm willing to splurge beyond the Pentel GraphGear 1000--and I'm not sure that I'm totally willing to go here yet, since I do tend to lose things, and I also have clumsy kleptomaniac kids which is why I can't Have Nice Things--I might go this route:
The rOtring 600 Drafting Pencil. I was originally looking at the Uni Kuru Toga Roulette (by the way, if you ever feel like you're a little too fanatically ardent about your pen and pencil choices, go look at the literally THOUSANDS of reviews on JetPens and realize you're not alone) but after hearing a few opinions about how the rotating lead-handling mechanism felt "spongy" and "bouncy" I was like NO THANK YOU MA'AM and turned my gaze towards to rOtring. Again, it's a textured metal grip, which I'm not crazy about--I really don't write as much with pencil as I once did, but I still do want to guard against sore spots and grip fatigue, in case I devolve into pathologic graphomania somehow--but the reviews seem good, and from a purely superficial standpoint, it really does look like a handsome writing implement with a price point to match. Anyway, I'll keep it in mind. I turn 40 in a few weeks, and if I decide to treat myself, maybe I'll go for it.
(Yes, I did say that I would consider treating myself to a mechanical pencil on my 40th birthday. Carry on.)
As I mentioned in the comments section yesterday, we are taking a trip to Japan in July, so if there's some crazy Japanese Hotness Mechanical Pencil (or any kind of Japanese Hotness office supplies of any flavor) that I absolutely need to source while I'm in the country, please do let me know. I know it's a family vacation and we should be visiting temples and eating sushi and doing karaoke or some shit, but hey, let's keep an eye on what's important. How else am I going to source cutting edge retractable click eraser technology except in Tokyo, I ask you? It's not possible. In America, we just have to use those giant pink hard trapezoid erasers like a bunch of savages. I know, it's tragic.