Just looking at your stars Robin, and it may be something to check in on that none of your optics are warped, Ive seen very similar star shapes come out of my 254 when the primary mirror was warped (see astigmatisim).
A very quick way to see if you have a issue is put a eye piece in and go in and out of focus if your stars start roundish then as you get closer into focus they turn slightly oblong then on the other side of focus flip 90 deg.. Start hunting!
The biggest reason why i say this is your extra spike on the larger stars. The rest of it is coma as you probably well know!
You are also on the money for not trusting the cheshire and the laser at f4.74 my 254 is touchy as a bugger, at f3.8 0.5mm out of alignment means doom! Good luck
