How's the passive mode tone? Does it sound as good as a passive classic Fender P or J, or do you pretty much need the pre-amp engaged to get the really good sounds out of it?
Most everyone prefers the passive tone best. Me too. My fretless L-2500 almost never goes to active mode.
The Tribute fretted L-2500 on the other hand while usually in passive mode does at times use the active settings. On that bass I have replaced the factory SIT strings with identical strings because they are so uber bright. Thus when needed you can pull some really nice slap tone or that low action "Conklin-style" tone with the very bright upper edge out of this bass. At times I've pondered changing strings to ground-wounds or the like to get a more traditional "fat" style tone and loose that ultra bright stuff which as others have noted really is a bit harsh. But for now I just like the versatility of having that bright top end there if I want it and I can easily roll it off if I don't.
My G&Ls don't have batteries either, but are powered by a TRS cable directly from the amp. That way the active mode is always there if I want it and I don't have to worry about dead batteries.