Hardness multiplier for adventures

How about a X2 - X5 multiplier for each adventure, this could be bought as you start your adventure at whichever level you want from normal to X5. The higher your multiplier is the more loot/bonus stuff you recieve but the time limit for adventure goes down too. This has got to make things more interesting especially for higher level players who have done most adventures multiple times but changing the time limits opens up a differnt challenge. AS for lower levels it allows them to do adventures to get more loot and upgrade things quicker.