I'm considering the addition of Vandersteen's 2WQ subs (stereo subs) in my rig and I'm looking for feedback regarding their performance when pushed, heavy rock/metal with intense bass passages. With the 8" drivers I'm a bit concerned about their 'speed limit'.

Can't help you much with the rock/metal aspect, but I have a fairly new pair of 2wq subs, and I love them, especially with the variable crossover -- which came in handy. Different settings, different responses.

Playing blues, rock (not metal), orchestral, etc.