Well, it turns out that those no-name KM-400s I mentioned are in fact ASRock boards. Here is a mini-review.
Price: Good. As cheap, more-or-less, as anything else on the market. 8/10.
Availability: Good. The key is to have a product that is available reliably, not here today and gone tommorow. No problems with these. 10/10.
Feature set: Pretty standard. All the usal stuff applies: on-board video, AGP slot, 3 x PCI, 2 RAM slots, single serial and parallel, 6 USB (1 each of 1.1, 2.0 and front-of-case 2.0), sound, and etc. 7/10.
Layout: Again, perfectly practical on the whole. My only beef is the absurdly difficult, non-standard and badly labelled connector for the LEDs and switches. Yuk! FSB speed is selected by a simple three-position jumper, which is as good a way as any and better than most. 6/10 (points off for the bad pinout).
Other: The AMI BIOS is dreadful. It pisses me off every time I have to use it. Believe it or not, you have to press F2 to get into setup! Huh? WTF are these guys smoking? Function keys for setup went out when the 386 came in. Then you discover that the avaiable options are limited and badly laid out, with all the most-used features buried well down in the menu structure. Worst of all, a bizzare WAD fault that I simply cannot believe: if you plug in a stand-alone slave device, such as a CD-ROM drive, it crashes irrecoverably on boot with a "system halted" message. Yes, it deliberately halts the system when you plug a CD drive or burner in! Minus 10 points for the worst BIOS I've seen since those appalling AMI Windows BIOSes that late-model 486 boards were afflicted with for a few months before Award showed them how to do it right.
Relibility & compatibility: Seem to be OK overall, but they are very fussy about RAM. You have to match them to particular exact brands, which is a pain in the arse. This is not something you expect to find in an entry-level board. Outside of that, no problems to speak of. We had one fail out of 30 or 40. Thought we had two more, but that turned out to be their RAM problem. 7/10.
Summary: The sort of board you buy when you can't get anything better.