I ask because I recently swapped out my Technomic for an SR quill stem that is 30 mm shorter for better fit. The new stem *does* fit much better, but it seems to flex quite a bit when I brake or accelerate heavily. Is this normal, are Nitto stems much less flexy, or am I just imagining things?

This is normal to an extent, but check for cracks. Nitto stems are cold forged, pretty much the strongest aluminum parts money can buy, so I'm not surprised that you would find them noticeably stiffer. Amazon sells technomics really cheaply if you want to got that route.

Yeah, that was my problem was that even on Amazon they're quite expensive compared to the ubiquitous SR stems you can purchase for $8, and I also couldn't find them in the size I want, so I picked up the SR second hand for cheap.

^ SR also made forged stems. Visually seeing a stem and bars flex may freak some, however they're more forgiving than a cast type.

Don't look down.

I've had good luck with the WIN brand that can be picked up on the cheap.

Everything Bicycles - : Kusuki Handle Works-`Win` Brand Handlebars and Stems*(see the picture gallery): Who's Who-Mfgr's of Components, Parts/Accessories & Employees