I've said it before, but I think your as well sticking with DBPro, and maybe taking a 'project holiday' to write a level editor that you can use in multiple projects. No level editor can replace a modelling package, level editors don't have to, in fact the very basics of a level editor could be done in no time at all.
The bottom line is that there is no level editor out there that's perfect for the way you work, the perfect level editor for a project is one made specifically for that project.
Personally, I always preferred the Oblivion editor to UDK or any other engine, the way the pieces snap together is just great - and that's the sort of thing you need. Your not gonna use the blivvy editor, and no other editor out there will support you snapping things together however you like. Have you seen the RealmCrafter editor? - it's a case of loading a mesh, scaling, rotating, and positioning - the sort of thing that can be done in DBPro in no time at all. If you want good options and an editor that does everything you need, then you need to write it yourself.
There is absolutely no reason why you can't keep on using DBPro for your game, everytime there's a thread like this, it basically represents a tombstone, with your projects name on it. You start flip-flopping between engines, hoping to find some perfect feature set, but it doesn't exist. All these engines are offering you neat terrain and level editors, but there are already great terrain systems for DBPro, look at BlitzTerrain and tell me that can't handle your project!. If you can model, then your level editor can be basic as hell, adding features improves workflow - and you'll know yourself which features will make a difference once you start working with it.
Look into terrain options, scripting, and making a basic level editor - it'll be the most productive thing you've done since this thread started, I promise. In the same time you could have a level editor done, you could have been putting maps together.
