Yeah, the only problem with the errata is that it makes the Tarrasques current Hit Points nearly irrelevant. The amount of subdual damage needed doesn't change if the Tarrasque is advanced in HD, or if you manage to reduce it's Con.
As Ryan pointed out earlier, they should have set the amount of subdual damage needed to "Current Max HP +30."
As Ryan pointed out earlier, they should have set the amount of subdual damage needed to "Current Max HP +30."