i have the pb12/isd2 and it is a massive house shaking beast.
you cant hide it but if you want "wow" factor for home theater then the choice is easy.
with the 2 you wont have to think about upgrading.ever.
ive heard the 16-46 and it is a great sub.it has a much smaller footpint.
if your ok with the size of the box then i would choose it over the 16-46.
scott