What's the problem with the Acoustic?
Behringer studio gear and stompboxes are actually very good for the (very low) price, but the amps do not get such a good write-up. Not sure why, but maybe there is a lot more inherent snobbery when it comes to amps? I would have though that the Acoustic was a much higher quality amp then anything made by Behringer, but that's not to say that it will sound better to your ears!
And wattage by itself is no guide to how an amp will sound...