I have owned both (and still own the EP pre).
The sound different. The PB used just as a clean boost colors the tone in it's own way-midrangey, and definitely has far more output.
The Dunlop sounds closer to the real deal, but it has some low end grunt and softens the mids and highs. It has far less ouput overall than the Duncan and one of the coolest things is you can set it below unity and it's like a "clean pedal"..it will keep your tone beefy but with less gain than the unaffected sound. So you can set your crunchy sound up, kick it on and get the sound much cleaner--it still stays punchy and big, it just seems to lessen the pre-amp gain. But as you get the least rotation on the knob, it cuts off completely. So you can use it as a kill switch or even an attentuator of sorts at the very minimum settings.
I had the Xotic too. Cool pedal, but IME with it, the EP, and the Belle Epoch, it's the least EP sounding of the three. The Xotic always seemed to muddy in vintage mode or too bright in "standard" mode. 9v or 18v. Cool clean boost, but not a great EP boost, if you get my drift. I much prefer the Dunlop, but the pre-amp in the Belle Epoch is significantly better than the Xotic or Dunlop.
The Pickupbooster is it's own animal. I preferred it's PUP color functions over it's actual boosting properties It was very noisy, and got muddy much above 9 oclock on the boost. But it sounded righteous with my strats in mode 1 or 2.
