Well that is one thing that I was trying to get at with this system. Although PL would be harder after a certain point, you could still choose to do it. I am one that doesn't wish to have limits on the skills you can learn, or how much Xp you can get in a limited time. To me I often can only get maybe one day to play in some weeks. When this happens of course I am going to make up for the time lost and really go all out to train and RP. As for the other point that was brought up from rtrentc. We know that the PP is temporary, even if this doesn't go in the final product, it might be worth trying since it may help us hammer out a new system. I figured that this might be a good starting point to work towards a better system.
One interesting thing I have seen done elsewhere is off-line training. It worked by for each minute you spent online your character could train off-line while you were away at a really slow rate. Say you played for 1 hour, then your character could train off-line at 1/8 of the rate in one skill. Just a thought though.