I have Eden WTDI. I use it mainly with Hagstrom HB-4 bass. The combination is very good, the sound is big, round and clean with heavy bass response. I use mostly the same settings all the time: bass, mid, treble - all 12 o'clock, gain ~25%, compressor ~25%, enhance 10-11 o'clock. I think it sounds the best this way. Sometimes I push "too much bass" button which makes the sound extremely huge and heavy but it looses definition a bit this way, this button is good for slow heavy parts like dub etc. Sometimes I roll off some treble depending on the cab. I like clean sound most of all (gain around 9 O'clock) or very slightly driven, if i try to push it more the sound becomes too rough and looses sweetness (to my taste).
Most of the time I run it into effect return of Marshall head into 8x10" cab (sounds amazing) or into the effect return of Behringer combo with 1x15" which is better then Behringer itself, but sounds a bit more quiet then Behringer for some reason. With Behringer I decrease Enhance to 8 o'clock, it's a bit too boomy with 1x15".
Another nice feature is additional output for PA console, so you can run this device both to the amp on stage and to PA simultaneously. Or I guess it's ok just to run it directly to PA on stage without any amp - light version for club gigs, when you do not need to carry heavy amp with you.
Overall, WTDI is a nice device, I like it.