Well, that's not really an easily answerable question. I have the PM 4.1's but I know darn well that the BA's are really good speakers (for computer use!) "Awesome Bass" What exactly does that imply? You have booming bass, bottom bass, punchy bass, smooth bass, pumping bass, and all those mean different things to different people.
Here's my take.
There's quality and there's quantity. You have to try to be objective about it. The Boston's sound very good, but if it's sheer volume you want, there's nothing else below $500 that comes close to the Klipsch.
And that's not to say the the PM don't have quality sound. They do. IMO, the horn tweeter does a lot to smooth out the sound. They sound awesome w/music. Forget imaging and soundstage....this isn't an audiophile-quality speaker review. Do the voices/drums/guitar/etc sound natural? That's what I was looking for.
I mostly game on my pc. If I want to listen to tunes, I have a pretty decent stero in the living room. But sometimes, I'll pop in a CD for background music while doing emails or spreadsheets.
I listened to both the BAs and the PMs. One thing that really sold me on the PMs is that the speakers have separate tweeters. One speaker cannot effectively reproduce as wide a dynamic range as two speakers, with each speaker dedicated to producing a specific range of frequencies. That's the whole reason why we have subwoofers, midbass, midrange, tweeters in the first place. Also, Klipsch actually gives wattage ratings, whereas Boston does not. You can hook up test equipment to find out, but hey, if you want me to spend my hard-earned bucks, you'd better tell me everything I want to know about your product and then some. Just by "seat of the pants" testing, I'd say that the BAs' put out about 2/3 the volume as the PMs. Ergo, 2/3 the wattage most probably.
The only way to tell which one is right for you is to "test drive" them yourself. There are some other very nice 4.1 setups out (theres' an Altec-Lansing...can't remember the model#) that's nice, but in the under $500 range, it's either BA's or PM/s. That's my $.02.