Vented and slotted discs are fine in slop, literally slings it all out due to the design. Drilled is where the issues occur.
@nobber good to know. May have a look see whats what.
That said I do I have uprated (suited to the current weight, had it weighed and chose accordingly) OME springs on the front and rear so plenty man enough for the job
You could get on a hill, 30mph, slam on the brakes and see if the front dives much, its the rears though that this effects more. Even worn springs can cause poor brake handling.