Doepfer

I've just about got the basic sound generation/modulation portion of
my synth completed, and now I need to start looking at subtraction. 
My gut instinct would tell me to get the A-120, but I remember reading
somewhere that the A-120 is fairly weak as far as filters go, and
there are others that can do the same effects and more.  For example,
you can get a low pass filter, high pass filter, or band pass filter.
 Is there a Doepfer module that maybe has all 3 combined where it's
more flexible?  Or are you better off buying the individual types of
filters one-by-one?  FYI I'm doing industrial music, so I guess a
primary use of the modular will be using really gritty sounding
saw-waves for bass lines, with the added bonus of being able to use
the modular as an effects processor for other sounds as well.  Of
course there's no limit on what I'm willing to do with it, if it
sounds good I'll use it.  :)

Also, I've heard mention of "sub-oscillators" somewhere.  What exactly
constitutes a sub-oscillator?  I'm guessing this would be a resonance
filter, like what you find on a LPF.  There's an EMS Synthi clone from
Analogue Systems, Harvestman has the Polyvoks, and there's the
Livewire Dalek and Vulcan.  As far as I know these all pretty much do
the same type of thing, just with slightly different characteristics.
 Am I missing something, or does Doepfer not have any of these more
unique sounding modules?  What I've heard of these things on youtube
is pretty impressive... just curious what options there are.  Not that
I'm wanting to stray from Doepfer, so far everything in my rack is
Doepfer.  :)  I might at least pick up the EMS Synthi filter some day,
as I love what it does when you run drums through it.

I appreciate you all putting up with my noob questions, just remember
you were all where I am, at one time.  :)  I've learned so much about
sound and synthesis already, and I'm still a VCA short of having a
"fully-functional traditional synth".  Once that module comes in, I
think a lot of possibilities are going to open for me, so I really
need to start doing some homework and getting some advice/suggestions
on where to go next.  I've seen a lot of people who have huge modular
setups, and do nothing but set up modular sequencers and play with
sound generation, but I'm more interested in integrating the
old-school modular with the new-school DAW software (Logic in my
case), so I'm doing a lot of midi work.  My case is 6U, and from what
I gather, with probably about 1 row of modules you can pretty much
have the equivalent of a Minimoog, so that gives me another row to
just expand this thing and get some amazing sounds on top of what most
people would consider "normal".  :)