I have to agree that drilled rotors are not needed for road use on a Triumph; in fact if you have to make a hard stop from high speed the mass of the rotor absorbs the heat generated, so more mass from no holes gives a smaller rise in temperature, less chance of fade. Then as you drive along the rotor gradually cools down.
For track use I use drilled Brembo rotors, with the edges of the holes chamfered to eliminate stress risers. This was done by a specialist brake company, KVR Performance, and I have never had a problem. In track use I will make several maximum effort stops every lap, and the flow of air through the holes helps cool the rotors, so this is a different requirement from a single "panic" stop in street driving.
Modern cars have ventilated rotors, which are really 2 rotors cast together, with vanes between them to act like a fan; lots of mass and surface area to dissipate heat, though because the cars are faster and heavier they will produce more heat in stopping. This is a different situation again.
In track use I have seen rotors crack from expansion and contraction, and even disintegrate with enough force to embed bits of metal in the car's alloy rim, but racing is a really extreme test of a cars braking system, pads usually last only about 200-300 miles!
For normal use solid rotors will serve you well, and are the best choice.
Simon.