I guess from your title that you are aware that stock Epics came with bass and treble tone controls, and do not have a low-pass filter (same as stock Orions and stock Excels) and so that, as the Q switch provides different options for how strong the filter affects mostly the attack part of your notes, you won't find a stock Epic with a Q switch upgrade.
Some Epic owners may well have swapped out the bass and treble controls for a filter (they're all modular) and as there are already four holes drilled, it would be only logical to include a Q switch.
Any Alembic sounds recognizably like an Alembic, just that the ones without a filter get to be perhaps a little bit less outspoken. Apart from the filter vs. bass and treble controls, the non-Series packages use the exact same pickups and the same uncoloured preamp. So any sound samples of a set-neck two pickup Epic or Orion with a fliter and Q switch will give you a fair idea of what to expect; with the Excels there's a couple of variables that might complicate an A/B comparison (ash body, pickup spacing, often a Fatboy in the bridge position).
Another suggestion is to give an idea of your general playing style - fingers vs. pick, jamband vs. metal, jazz vs. reggae, etc. etc.
