skunk2 just made the focus application. So I don't think you'll find a single user on this board who owns those springs.
tein springs are quite on the softy side if you check the spring ratings thread in the top of the suspension forum (the sticky note)
I bet they are about the same as far as the lowering and ride-quality. I am assuming that both, tein and skunk2 are progressive springs. meaning as the spring get's more compressed, it becomes progressively stiffer.
They both are probably Ok to ride on, But if you want something better I'd suggest H&R cupkit, or a complete eibach setup.
Don't get these springs and install them on the stock dampers, or else you'll have quite a bouncy ride after a some time.