I'd suspect the crank Sensor
My 1100 Monster was doing the same sort of thing, it started a couple of months ago and slowly got worse, often cutting out when cold and hard to start, it got to the point where one evening it took ages to start.
I purchased another crank sensor but before it turned up I seem to have cured it by playing with the connector where it plugs into the main loom.
Now starts every time and no more cutting out.
At least I now have a pickup ready for next time
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