I have these on both Bromptons, the Street machine and the Catrike - I was let down once, but after spending 40 minutes looking for the p*nct*re I found a small split in the tube near the valve - so nothing to do with the tyres (still 100% record)
They are a little slower, but not greatly. My personal view is that if I lose 15 minutes a week and don't spend 15 minutes repairing a p*nct*re then it is a gain overall.
Both the thorns have Marathon XRs, but these will be changed for MP+ when they start to wear.