The old W3s are based off the W6s. All things being equal you couldn't tell witch sub was the W3 and witch was the W6. Maybe the only way you would know would be by looking at the cone. In fact the W3 has somethings that the W6 doesn't have so in some ways you can look at the W3 as a better woofer then the W6, but thats before the v2's of both versions have come out. The new W6 in the little brother of the W7 and the new W3 is a rework version of it's old self. Either way that you go with two W3 or 3 W6 you are it's goign to sound good. The 3 W6s is going to be louder because, will you have an extra speaker.

Just do clear something up here. The W6 doesn't have a weird impedance. It is a DVC with 6 Ohm coils. This is the reason it's called a W6 because the coils are 6 Ohms. Now I know that it sounds weird but follow me for a second.

I hope that everyone knows that with a DVC sub you can get two different final inpedances from the sub. With a DVC 6 Ohm you can get a 12 Ohm sub (series the coils) or a 3 Ohm sub (parallel the coils). How that you are armed with that lets take it a to other level. Now you have three subs and you need to get the best impedance at you amp. Lets make this easy and say that you need to get 4 ohms at the amp. Now look at it like this you either have 3 12 Ohm subs or 3 3 Ohm subs. Now do you want to series the three subs together or parallel them. Well lets to the math. Lets start with the 3 ohm set up, since we paralleled the coils on the subs we have to run all three subs in parallel by doing the math of 3 ohms/3 subs = 1 ohm load to the amp. Not the 4 ohms we were look for. Now with the series setup 12 Ohms/3 subs = 4 ohm load to the amp. Thats the set up that you need for the amp. Just remember this 6 Ohm coils are for run subs in odd number combos like 1 sub, 3 subs, 5 subs.