Hi Rob, there's another recent post (I've seen it in the last few days) by someone who has used an LED relay/flasher unit with standard bulbs and it is looking as though the standard bulbs have, over time, damaged the LED relay - probably by drawing too much current & eventually the flasher unit has given up (overloaded/burnt out).
Fact is standard (incandescent) bulbs draw plenty more current than LEDs. If this wasn't an issue, then Triumph probably wouldn't go to the trouble of 2 different relay/flasher units.
An LED relay/flasher unit may work with standard bulbs for a while, but the high current draw is likely to shorten the life of the unit
Ps. I'm not talking through personal experience - just a little bit of electrical/electronics knowledge and seeing what has happened to others.