This evening I replaced my standard brake/running lights with LED replacements. The original part is a standard 7443, wedge-base bulb; I put in 45-LED red replacements (at about $25 a pop...). The results are mixed. I think that, as running lights, they are a bit brighter, but there is less of a change in brightness when the brake lights come on.
Not surprisingly, the bulbs are polarized; if you put them in the socket the wrong way, they will not come on. They seem to fit either way; I just had to try them both ways to get them to work.
I also replaced the bulb in the trunk with an LED replacement; it's brighter and yet uses a lot less power. Since many Reflex owners have reported that the light in the trunk can sometimes stay on and drain the battery, this gives me a little more confidence about letting the scoot sit for a while without running. Again, the part is a 3022, 31 x 10mm "festoon" bulb.
I'm now thinking about replacing my turn signal lights. These present another challenge; the lower current requirements of LEDs tend to cause problems with the standard turn signal relays. Special LED relays are available, but I'm having trouble locating the right part. The standard Honda relay is Honda OEM part # 38301-KK9-952; this is the same as a Mitsuba FR-3303. Searching on those part numbers, though, for an LED-compatible replacement hasn't turned up anything definitive - yet....