Jason:
Coming from the Presbyterian side, I can tell you there are many Presbyterians (including office holders) who take the WCF seriously yet don't agree with every single word. If their exceptions to the WCF are few and are considered minor, those exceptions often are allowed and that person can still be considered one who "subscribes" to the Confession. Maybe that's why you think of yourself as subscribing to the WCF.
However, I know of no Presbyterian denomination that takes the Confession seriously and allows routine exceptions to the doctrine of infant baptism. Such exceptions simply are not considered to be minor. So to avoid confusion, I would say it's best for you not to claim subscription to the WCF if you disagree with infant baptism.
On the Baptist side too, the baptism issue is pretty much an across-the-borad non-negotiable. The simple fact is that we have substantial disagreement on this issue, and both sides consider the issue important enough that it's not one to fudge on. For the vast majority of churches, the differences between the WCF and the LBCF on baptism are held to be much more substantial than any differences they may have on reprobation.
So to communicate clearly to the rest of the Reformed world where you stand, it seems to me you'd be better off saying something like you subscribe to the LBCF but prefer the WCF's position on reprobation. It just makes more sense to the rest of us than for you to say you subscribe to the WCF. And communicating to each other where we stand is a big reason why we subscribe to confessions in the first place.
