They are surprisingly reasonable to insure, considering the performance. When I first insured mine three years ago I was changing over (mid-term) from my 1993 Volvo 850GLT 2.0 ltr 10v, with a 0-60 time over ten seconds, plus it was valued at just over a seventh of what I paid for the Brabus, yet unexpectedly I had to pay no additional premium for the remainder of the year.
On a somewhat related note, my renewal is due early next week so around a fortnight back I went online and switched insurers for the first time since 2017 (probably stupidly, I still have a bit of that loyalty thing loitering in my psyche, so I don't like swapping every year) and saved myself over twelve quid a month. While I was getting my quotes I did a bit of fiddling with the options, as I usually do, and this time round I played with the excess settings, to see what difference it made. I always have a zero voluntary excess, on the grounds that I'm paying to have the insurer cover any damage, so why bark myself and fork out money when there is no necessity. I selected a hundred quid excess and was surprised that it only dropped my premium by forty pence per month. Therefore I clicked to two hundred and fifty quid for a better result. However, I was raising eyebrows as the premium was now only eleven pence lower than with a zero excess. Curious, I decided to go big, choosing the maximum five hundred voluntary. Astonishingly, the monthly payment was now six pence more than with no voluntary excess. My mind was utterly boggled. I used to work in insurance and know how tricksy these companies are, still it seemed totally illogical. I can only guess that it says something about what the insurers think of people who choose to have extra excess on their policy.