As I said, probably not; Chinese batteries are usually overrated, with very few exceptions. I've used grey Trustfires before, and I've found them to be anywhere from 2 to 2.3Ah (that is, 2000 to 2300mAh) depending on the phase of the moon.

I should mention that Ultrafire are a more known brand, but they cheat a lot more on the stated capacity and actual quality of the cells. I'm a member of the CandlePowerForums board as well, and many users there have conducted extensive testing of Chinese Li-Ion cells; Ultrafires consistently disappoint, but Trustfires have come out as a good bargain-basement choice. They don't have the capacity or durability of Sanyos or Panasonics, but at $3.5 a pop it's a compromise I can make.

I could always just bring my backup phone (unmodified Motorola Droid 2 Global) if simply going on a short vacation; I wouldn't have mobile data anyway, which limits the uses for a smartphone, so I could stomach going back to Android for a few days.

Problems would arise if I were to stay somewhere for a few months... I'd carry the N900 with a normal battery and either backless or with a replacement back casing, but I'd want to carry the big triple-barreled monster at least in the suitcase so I could use it at my destination. What's the proper procedure? Do I go to the security people and say "look, I've got this battery I have to carry with me, but I need you to see it now so you don't think it's something entirely different"?

I doubt there's such a thing as a genuine 3.8Ah 18650. Last I heard the big guys (Sanyo, I think) had just barely managed to make one that held 3Ah, and even that wasn't being sold in great numbers; I'd be surprised if a 3.8Ah 18650 could even be made with consumer-level technology.

I like the idea of a proper body, and if I had a 3D printer I might try to make one, but as it is I'll just slap a square of plastic on the whole thing and call it a day. I just want something else than the bare cells to act as a contact surface and bear possible impacts.

My RC charger only discharges at 1A maximum, but since I used relatively thin wires even that'd probably drop some voltage along the way. I'd have to discharge at 500mA, which would take most of a day. Maybe one day I'll do it, but don't hold your breath.

I'll give a look at the app in your signature.