Depending on which way you want to go with this. Having both lamps on (Dipped and Mainbeam together) won't do you any favours with other road users (assuming they care) if not enough light output when you need to be in dipped mode which was the problem I experienced.
- I ran this happily on my Uly for many years and upgrades your existing light unit to twin H4 lamps.https://www.lightningleds.nl/
- Gets you a brand new, purpose built twin LED light unit. I purchased mine earlier this year but haven't ventured out at night with it yet (not had a need to be out at night). Did pass the MOT with it last month so no concerns on that part.
Got a friend with a XB12XT with the Red Fox and he has stated that it is definitely worth the money. He's using it a lot right now as it is dark at 5 pm these days.
I prefer having both lamps on if possible simply because a larger area makes you more visible to other vehicles. Tiny projector lamps may put out a decent light, but they're so tiny to other road users that it's easy for them to not really identify you. For me it's always about being seen because that's something I don't manually have control over. I can personally handle what I can see even with crappy lighting.
Best lights I ever had were on a Moto Guzzi Stevio NTX. Best part of the bike actually. Big lenses and big output. Like the sun was in my fairing nose.