I have been using two Hähnel MODUS 600RT Speedlights as part of my Speedlight arsenal for a couple of years now I think.
Very pleased with them. They dovetail nicely with my Nikon Speedlights in many ways. Very well in fact.
A range of light shaping/changing accessories have been announced, which, via one of two clamps will fit the range of MODUS flashes magnetically to many Speedlights/Speedlites on the market.
I have not used them yet, but they make a logical addition to the system, plus an alternative third party option for many Speedlight/Speedlight shooters looking too control lighting.
I also like the responsible approach to packaging the brand is taking.