I've been playing through the WTX-260 since last November - I got one of the first-runs. I've used it exclusively with a big band and a quartet/quintet for weekly rehearsals and about 10 gigs so far. It's running through an Eden CX110 cabinet, which I raise off the floor. If I don't raise it, this setup would shake the whole band off the stage.
It's used mostly with my DB through a Revolution Solo, which puts out a lot of bottom end. I also use it with my EUB and a G&L 5-string.
I've never had a problem with volume using this setup, though I have had to push the master volume to about 3 o'clock. I previously used an MB200 and then a GK400RB through the same cabinet. The MB200 was seriously underpowered, and the 400RB head was a pain to carry around. I really like the sound, once I found the right settings. The EQ-compression-enhance settings change dramatically for each of the 3 basses, and it took some experimentation to find the right combinations. If I played much arco live, I'd have to come up with a 4th setting. At medium to high volumes, it's not a completely transparent setup, but does it matter when it's that loud? It cuts through the band and sounds really good on live recordings. At lower volumes, it sounds like a loud version of my DB.
I am really happy with this setup because of it's size, weight, and power - the head goes in my backpack along with charts, cables and my tuner. I theoretically could do one trip (without a music stand), but I'd rather not wheel a DB around with one arm if I can avoid it.
I did have a problem with the sound breaking up sporadically. I replaced the 1/4" speaker connection with a 2' cable and neutrik connectors, and the problem went away. I'm not sure if it was the connectors or the cable being overpowered or maybe just going bad.
The head weighs 3.8 lbs. Eden will be coming out soon with a combo with this head and cabinet, except it will use Neodymium magnets that significantly reduce the speaker weight.