What should the starting Feruchemy rating for a Ferring be?

[oxinabox]

Ok, so I'm working on my own set of house rules for Alloy of Law,
and I'm trying to work out ratings for Ferrings (Single Metal, Feruchemists)
I had been going with:

For Starting:
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2.1.1 Powers (new options)

Strong

• Twinborn: Your character is both a Ferring and a Misting. He or she has a Feruchemy rating of 5 4 in one metal, and a Allomancy rating of 5 in a different metal. (Note: for a normal Twinborn these must be different Metals, if they are the same, you are a a Compounding Twinborn. see below)

• Compounding Twinborn: Your character is Twinborn for the same metal. This means he or she can Compound ([sec:Compounding]) He or she has a Feruchemy rating of 4 3 and a Allomancy rating of 3 2 in the same metal.

Average

• Ferring: Your character can store and magnify any number of personal qualities. He or she has a Feruchemy rating of 5 4 in one metal, and may use Feruchemical metalminds of this type (see page 275 of Core).
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And for advancing:

Improvement	Cost	Description
Become a Twinborn	-	To become a Twinborn (or Compounding Twinborn) you must purchase appropriate "Become a Ferring" and "Snap into a Misting"
Become a Ferring	10	(Characters without Feruchemical powers only), become a Ferring with Feruchemy rating of 4 3 in one metal.
Become a Ferring (such that you are a Compounding Twinborn)	20	(Characters without Feruchemical powers, and with matching Allomantic Power already, only), become a Ferring (and thus a Compounding Twinborn) with Feruchemy rating of 2 in one metal (and maintaining your existing Allomancy rating in the same).
Become a Misting (such that you are a Compounding Twinborn)	10	(Characters without Allomantic powers, and with matching Feruchemical Power already, only), become a Misting (and thus a Compounding Twinborn) with Allomancy rating of 2 in one metal (and maintaining your existing Feruchemy rating in the same).

Now I'm yet to stat out compounding, but ignoring the number that are there to balance around that (since I haven'tmade therules that use the numbers) that we still see a oddity that worries me:
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Problems: A.1 Feruchemist starting ratings

Ferrings (starting rating 5), Twinborn (starting rating 5) start with much higher Feruchemy ratings than Keeper (starting rating 3 in all). This gap is bigger than the gap for Mistings (starting rating 5) and Mistborn (starting rating 4 in all).

The reasoning behind this is that Becoming a Ferring (rating 4) should be worse than starting as a Ferring, and becoming a Compounding Twinborn (rating 2) should be worse still.
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What do people who've actually played think?

I'm was worried (Prior to latest edit) it wouldmean that For Ferrings, the will be no where to go - they are more limmited by there physcial attributes limits (Like you can never store more than you health-1 charges in gold in an hour).

EDIT:
Should this be in the License to Improve board?
EDIT 2
here is the link for the current version of the fansupliment.
http://www.crafty-games.com/forum/index.php?topic=6148.0

EDIT 3
The Strikeout stuff

[ReaderAt2046]

Here's how i would do it:

Starting Powers:

Strong: Compounding Twinborn: Allomancy of 4 and Feruchemy of 3 in chosen metal.

Medium: Twinborn: Allomancy 4 and Feruchemy 3 in different metals. Ferring: Feruchemy rating of 4 in chosen metal.

Advancements: Snapping into a Ferring costs 10 advancements and grants you Feruchemy 3 in one metal.

If a Misting or Ferring Snap would make you a compounding Twinborn, it costs double, but you still gain Allomancy 4 or Feruchemy 3 as usual.

[oxinabox]

I only charge Mistings becoming Ferrings such that they are twinborn at double, bacause taking that path makes you much more powerful than any other (you start A 5, F 2) which because of my rules for compounding using your allomancy rating as a multiplier, makes you twice as effective.
Though you moved other things around to. so...

BTW
My compounding twinborns are alot weaker than they are in the books (not so much from my rules, as from the difference in ther amount of time it takes to Store vs Tap.

I'll take a good hard think about making twinborn medium, in ther way you are showing.

[ReaderAt2046]

My thougts on ratings, by the by.

Ferrings are 4 because of the precedent of Mistings being one higher than Mistborn, and Snap at 3 because of the same precedent. Twinborn have less focus in each field, so they start out at the Generalist level in each field.