As you can tell from my signature, I'm also a fan of Markbass amps. As a comparison I'd say that tonally these two are not miles apart - but there are differences. The Eden has better separation of notes in the lows (very clear voicing) and a more hi-fi/studio sound all around, whereas the Markbass has a bit more of a traditional bass amp sound to it. In other words, if I had both and needed to run one of them for a keyboard rig or P.A. I'd use the Eden - it's more polite. Also, I run the tone on the Eden almost completely flat which gives more headroom if needed.
As pluses for the Markbass LMlll I have to say it has noticeably more power and because it is so small and doesn't require a rack mount, it's much easier to hook up and make wiring changes. Also, when I do need to make tonal changes, they just seem to be easier to do on the Markbass. The 405 only has two mid frequencies in the tone section as compared to some other models - that's why I recommend using a separate eq with it.
As far as overall personal preference, I'm totally happy with both of these amps. If I had to choose I'd say the Eden is the better and more flexible amp, but I often pick up the Markbass for convenience and more power. And even though my group doesn't play very loud at all, I'm already running out of power on the Eden and am going to have to switch to a more powerful amp in the near future.
Sounds like others on here are getting plenty of power out of theirs although every band/gig/room is different.