At risk of derailing the discussion a little from just the two brands/types in the OP

; have you tried Innovation 140's? I'm currently running the 140B D&G and the 140H E&A and quite like 'em (although am keen to get my Anima's back on; long story, see the Velvet MTII if you're really bored with nothing to do); although it's been a while since I had my Spiro Weich's on, they seem to be a little thumpier than the Spiro's with a little more tension (but not uncomfortably so; if anything, I find the extra tension allows a little more dig-in and gives a bit more feel back thru the fingers). They're pretty good under the bow, too. Must admit, I've not tried EP Weichs though; they're hard to get here in Oz.
Also, if you're chasing more volume, perhaps try a Marvin tailpiece? My bass opened up heaps with one, although I do need to be a little careful about a Bb resonance; the top vibrates a lot more freely now! Interestingly, swapping between a metal & wood endpin does change that too; metal damps it but also lowers the apparent volume; seems to force the resonant peak lower so it sounds bass-ier but hence softer in the 'voice'/mids.)
Right; back to normal programming...