well, i'm a user of the EBS and i think it's pretty cool. what attracted me to it was the effects loop. the benefits of the loop are that whislt recording, all my distortion and fx are going through the loop then i can just tap out from the pre-amp's XLR out (much like the bass bone i reckon). in my opinion, routing your fx this way keeps your tone a little more congruent as the pre-amp has more control over your overall tone as compared to running the FX in series with the pre-amp at the start of the chain.
i've also tried the Sansamp.. it's got it's own character which some really dig while some would say colours your tone a lot.