Adding to #9.
I must stress that when comparing wet and contaminated data, the information is not necessarily 'like-for-like'.
Wet landing performance includes a runway distance safety factor (1.92), and normally does not assume the use of reverse thrust; as conditions deteriorate the safety margins reduce rapidly, i.e. we might depend more on reverse.
Contaminated data under EU rules most likely assumes reverse thrust (see AFM), and the data might only have a distance safety factor of 1.15 (EU-OPS 1.520).
Thus in extreme conditions, whilst the published distances for wet and contaminated landings could have similar values (contaminated must not be less than wet), the basis of the calculation, safety margins, and thus the risks in operation are completely different.
The contaminated distance margin of 1.15 might only represent the difference between the theoretical minimum distance and the distance which line pilots can achieve on a regular basis, i.e. there is no distance safety factor.