Starting Grades... Why now?

Realizing that for the first time, I have a logic student this year is still a bit mind-boggling to me. (Where did all the time go?) I know that 4 years from now when she reaches the rhetoric stage I'll probably still be wondering the same thing. Anyway, as part of ramping up the work for the logic years, I put a lot of thought and prayer into whether or not to start grades with Jessie this year.

Pros:

• practice for me - This gives me a couple of years to establish a fair system and work out all of the kinks
• motivation - Jessie is a perfectionist so simply knowing that the work is graded will result in a better effort than just trying to complete an assignment well enough for me to call it done
• record keeping - While it is unlikely that anyone but DH, Jessie, and I will see her grades, there is always a chance that if something were to happen to me Jessie would need to go into public school. Since middle school classes are leveled based on ability, I think the grades in combination with examples of her work would make it easier for her to be placed correctly should it ever be necessary.
  
• constructive feedback - I'm hoping that by quantifying her work that we can constructively discuss where any given assignment can be improved to really start seeing improvements in her writing and other more subjective areas of schooling. The goal is to have things done well not just completed so we can move on.

Cons:

• motivation - Motivation for Jessie is a two way street. Since she will naturally expect herself to score a 100% every time, I'll have to make sure that she doesn't become overly discouraged when that happens.
• time and effort - I know that grading will take more time and effort on my part than reading a paragraph and saying, "That's fine," but I'm hoping I can keep it simple enough to stay on top of it.