Regarding the new example, the amount to ask to be recharacterize is $1,000, the same as the amount of the contribution. The amount that the law requires to be transferred to accomplish a recharacterization of the $1,000 contribution is $1,333.33 because the entire account experienced a gain of 33.33%. The $333.33 is treated as investment gains in the receiving account.
The gain or loss on individual investments doesn't matter. All that matters is the overall gain or loss in the account during the computation period. You could sell all of the original shares, buy different shares, hold cash, etc., and that doesn't change the calculation of the attributable net income. All that matters is that the account was valued at $6,000 immediately after the contribution and that the account is valued at $8,000 when the recharacterization is performed, indicating a 33.33% gain.
Consider the case where you sold all of the original investments so that you had all cash in the account, then later purchased some other investment with all of the cash. The result would be the same if at the time of the recharacterization the account value was $8,000, a gain of 33.33% from the $6,000 value immediately following the contribution. The performance of then individual investments in the account is irrelevant to the computation (except for how they contribute to the overall gain or loss in the account).
