Maybe I missed it, but what happens to your existing WPP expenditures? Say you have 120 1h and 100 throwing, but you end up losing wpp; which proficiency loses those points?
If this is handled incorrectly, I could see throwers getting screwed with "your proficiency is too low" message with no recourse.
EDIT-I say no reimbursement of str, but offer my proposed "mini-respecs" in the store ;-) Make those people that have been crutching strength for 2 years with 0 WM at least have to pay some gold to get agi/wm.