ok.. so I have FINALLY gotten sick of my SansAmp BDDI. It just doesn't get me the sound I want. I use it for a pre-amp and then into the Mixing Board at church, so I don't have to set-up my full rig on Sundays. I am looking for a replacement, and have come across these two. The signal chain is Bass - Effects - Preamp. Since neither of these have XLR out, I'll be sticking it into a Radial DI. What I am afraid of is that these are designed really as outboard versions of onboard pre's, and won't work well after several effects (compressor, chorus, reverb) Thanks for the assistance.
I don't have direct experience with either one, but I wouldn't worry about them being "outboard versions of onboard pre's". Reason being that there's no inherent difference between an "onboard pre" and any other kind of pre. They are all designed just a bit differently, so you have to take it on a case-by-case basis.
I can't comment on the Agie or Demeter ... BUT I have used the Bassbone and, for me, it's just fantastic. It's not going to color the sound a lot, thought he EQ is very nice (I even like the presets). It's also got a Radial DI, which I've found to be the quietest DI I've ever used. You mentioned effects ... It's also got a switchable loop/boost. So you can take the pedals that suck tone out of your straight loop. I keep the true-bypass ones in-line. If you like the sound of your bass direct, then this is the one I recommend.
I have used the Demeter and thought it was fantastic. I would still be using it if I didn't have an RBI now in my configuration (I added the RBI to use both as a DI and a pre).
What about a Sadowsky Pre? It has an XLR out. Edit: Sorry, after re-reading, it appears you are looking for Tube tone.