UPDATE: Due to not liking the mismatch between my "Cool White" map light LEDs and my more natural light Ikea footwell LED lights, I decided more experimentation was required... so while ordering the WLED-CW5 replacements (the 'Natural White' WLED-NW5's), I also got some alternatives to play with. Cutting a long story short, I found that the 921-x12 Wedge Base LED bulbs were much brighter even than the WLED-x5's -- subjectively about twice as bright (sorry Goat, if I'm about to cost you more dinarii

).

I played with swapping both sides, and decided that the 921-x12 were actually TOO bright for the driver side, this mostly due to reflection caused by the angle of the mirror throwing the driver-side light directly onto the console, whereas the passenger light is shines mostly out into the knee/seat area. So, in the end, I found a perfect balance using a WLED-NW5 (or CW) on the driver side, with an 921-NW12 (or CW) on the passenger side. Here's a photo of my hands in the cones of light - giving something of an idea of the brightness difference and balance (not as obvious a difference as you see in reality though).

The 921-x12 bulbs are $6 each in white ($4 in Amber, see below) or $2 more each than the WLED-x5 bulbs.
So, along the same vein, I also tried the 921-A12 (Amber) for the side marker lights. They work well, giving almost exactly the same amount of light out as the standard incandescents. I'd say these are particularly advantageous if you've done the 'turn-signal mod' since they will stress the flasher circuit less and have a much faster on-off time. Here's a stitched photo showing a comparison (taken at the same aperture/shutter speed). The original bulb is less bright in the center, but more diffuse... overall about the same light throw:

Next, I'm going to try the WLED-CW5 bulbs I removed from the map lights in place of the rear license plate bulbs. Stay tuned...