Actually, some of those have online shops that deliver just fine. I think that "don't buy suspiciously cheap stuff from people with zero guarantees and low ratings".

I order stuff from China routinely and am yet to be disappointed. Though I stay with high feedback and shops.

The Kingston site has 16 GB Class 10 cards for sale. I put one in my N8 because I wanted the speed for video recording. It works fine. I usually buy direct from the manufacturer to reduce the possibility of getting a fake chip.

I've had to warranty one Kingston microsdHC in the last four years, an 8gb Class 4 that separated when I inserted it into my N78-3.

Hard to know, you'd need to know if someone has one, and that that person also has a N900. Its really hard to know if a FAT32 FS can handle 2Tb, and if the device can browse it all. What i would consider is this: splitting it in half and formatting the card 1Tb/500Gb for a desktop OS, 1Tb/1,5Tb for storage/FAT32.
That would at least limit it a bit... And, you could always try out 32, 64, 128, 258 and 512Gb partitions and see how far it can go with a kind of FAT filesystem.

If the N900 did support 1Tb... it would be the best MID in the world...

The theoretical maximum size of a FAT32 volume is close to 8 TB. In practice, many applications, utilities, and drivers probably have much lower limits. For instance, Linux--including Maemo--supports only up to 2 TB FAT32 volumes.