Link to the sub amp modual i want to install into a HWK
http://www.jaycar.com.au/productView.asp?ID=AA0509&CATID=15&form=CAT&SUBCATID=44...
Looks like a nifty lil unit

I agree with DanK, in that a combo is better that trying to do it all with one type of box.

I never DJ'ed (I actually hate people, but I love BIG sound!!) but I have rented many of my systems to shore up the sound of small DJ operations. My "low bass dual eighteen folded horns"  in combination with my "ported and front faced mid-bass horns"  was a combo that was hard to beat for large crowds in medium sized venues.

Two big boxes (horns, twenty eight cubic feet each), two medium, midbass boxes (horns, eight cubic feet each), four large mid/high horns (four cubic feet each) and four high horns (all the mids and highs are splayed for dispersion) and about ten or twelve KW per side, quad-amped, would do everything we ever needed in most venues.

I don't think you will find a single design that will do both small crowds and large crowds.

For smaller crowds in larger venues, I usually just brought in one large bass box and set it in a corner and the main house system was just the upper three sets of box styles. In fact, for many venues, I would often leave out the lower voiced high boxes and just use the one dual eighteen horn in a corner, two "midbass" boxes and two HF horns (one low-mid and one high per side, bi-amped with one sub out to the lows in the corner).

The other thing worth considering is what kind of music are you are playing. It would be difficult to do modern rap without some rumbling bass and it would be silly to use that same bass system with a typical country crowd.

Melbourne?

That changes everything!!

... doesn't it?

Pop and R&B, modern Alternative/Indy, old school classic rock ... you can likely skip the giant bass boxes and get by very well with a couple of WOs for most medium sized venues.

I have only had one chance to "let fly" at high power my one dual fifteen Housewrecker and to be most honest, I had more bass outside the building than I did inside. I believe this had to do with the dimensions of the building and what nodes may become a problem, but (it was a five hundred table, low roof party hall with a small, central dance floor - I am sure that Steve can eloquently describe the acoustical anomalies we were facing, with no further description of the hall - I would be forced to use harsh expletives, however) the bass was there, but it was more powerful well outside the dance area.

WOs (probably four of them) would have been a better choice due to their directionality and the concentrated force of their airflow.

I only have used four WOs with one local band (but for over three years now) in various small venues, but with two per side, their compact "club PA system" is quite impressive, to be most humble about it (we set them up in various ways - sometimes all facing forward, sometimes, facing at various angles - occasionally both facing towards a corner - you just have to be willing to think as you set them up, because they don't always need to go forward with the rest of your speakers - be flexible).