Have an issue w/ my '02 Bird: The FI light will sometimes, randomly flicker (occasionally staying on steadily for up to several minutes). This is accompanied by rough running and lower power. Once, this shut the bike down while idling right after I started it, though it did re-start and got me home.

This is very random - it's occurred riding down the interstate, idling in a parking lot after starting, whenever.

Search turned up lots of info on the test block fix for the wiring harness on '99 & '00 Birds with this issue, but nothing on the newer bikes. Do the '01-'03 bikes have a test block, or are there similar weak points in the wiring harness (I'm thinking of the set of wiring connections under the gas tank on the left side)? Any other things to check out?

Check for any loose connection on the grounding area.Not to forget check the ECM unit whether any frayed pins.

First thing that comes to mind is to check your battery connections and your main ground if you haven't already done so. Flickering FI lights on Hondas with no actual FI code are usually ground related in my experience with 2 different FI Hondas, Bird and VTX.

Edit - Dangit, Greysnail beat me to it.

oops - forgot to mention - a few nights ago I took the harness ground terminal off (the one on the top shock mount), scraped the frame really well there w/ sandpaper, and re-installed the ground terminal, with plenty of dielectric grease applied over the works afterward. Still had the same issue last night coming home - almost cut out while buzzing home on the interstate.
The FI light stayed on solid for about a minute, then flickered less and less until it was fine again.. No such issues this morning on my 25 mile commute... We'll see this afternoon...

From looking on the UK XX sites, YES some later Birds have had problems with the loom even though the connector is in a different position

How old is the battery?

Have you checked your ECU for fault codes? The light can flicker sometimes when there's a stored code. There's a procedure in the manual.

check the ground connection under the tank by the shock mount for clean and tight.