My point was I have difficulty making sense of the PC saying "I want to make an easy negotiation skill." And easy climb vs a hard one, I can see numerous ways this could go (different walls, using the environment to help you get over but taking more time).
The diplomacy a little more difficult to understand how the PC picks that. One suggestion was that an easy DC means corrupt guards. My reaction to that was, what if two people pick it and succeed, and a third PC tried is as well...that implies that in this chase we have three corrupt guards? In certain cities, that may be fine. Others, however, that makes little sense.
It's logical justification for such things that make PCs being able to pick easy, medium, or hard difficult for me to grasp as a concept and to play out and describe as a DM.
I suppose it is just as likely that the easy diplomacy check could represent the character stopping his running and turning and talking to the guard. It allows him to be heard better and shows a certain amount of trust and he is no longer running. The guard however, catches up so if the gamble fails, he's right there. The harder DC could represent the PC booking at full speed, yelling back whatever he can. He's not making a a strong argument and is more concerned about getting away, but if he says something that strikes a cord with the guard, the guard falters in the running and the PC increases his lead.
I have always been a fan of one roll with multiple DCs for varying results. There would be easy, medium, and hard, but since the PCs weren't shooting for one, they could get any of them. The PCs trying to get an audience with a local lord. They roll one check and if they hit DC 15, they would get an appointment in a week or so. DC 25, it would be a couple days. DC 30, and it's "wait here, we'll see if he's free right now for you."
This new system seems as thought the PCs would pick which one they wanted, and if they tried for the harder, "right now" check and failed...it is a failed check on all accounts. Obviously as the DM I can say that it was high enough to get them an appointment within a couple days and not have it be a total failure, but I am curious to see what the skill section says about this. Previously I rewarded skill checks that were extremely greater than the DC. This system might be limiting that since, if someone picked an east DC and someone else picked a hard one, and they both end up rolling natural 20s and getting the same results, the fact that one was a harder DC should sway the action more than the amount the roll beat the DC (if that made any sense).