Birroc, depends on your budget & preference for roof finish. If you want a very smooth looking roof, black in colour then the Thrutone's are probably what you're looking for. If you prefer a more rustic, natural looking roof with a grey/blue hue of it, then a natural slate is your best bet. The other major consideration is how your roof will weather. Invariably, the Thrutone will fade as its a 'painted' slate with a cement substrate, while the natural slate should retain its beauty for the lifetime of your roof. I've just completed my roof & we used a natural slate from LBS (Lagan Building). Its a Vigo 7mm slate (Spanish) with a dary grey/blue hue and we're delighted with it. Really adds character to the house compared to the Thrutone (in my opinion) albeit working out more expensive. As far as I know, the Vigo is also marketed by Richmond as a Samaca Q49. Good luck as its a big decision......apple1