For grass, if i remember they have some special feature called mini mesh,
sort of optimised duplication meshes.

For scene , i htink it's to you to use some LOD depending on your game style.
if outdoor like in Oblivion , LOD with paging could work.
I don't think they have some real scene management.
But again depends really on what you want to do.

For editor, browse their forums on showcase or announcements :
planetX
PlanetX seems a good one.

showcase forums

Appart from that, It's next gen, with dynamic lights, nowadays shaders ready to use.

some users have done some little cool flight game or a american football game and some interesting things.

Well if i had to choose between Blitz3D, Dark BAsic PRo :
it would be this one indeed , lot less code to do than Blitz3D, lot more powerfull/functions/fast in 6.5 than Dark BAsic Pro.

I've tested lightmaps exported from 3DSMAX , works well, but 3DSMAX not cheap for everybody
A map editor generating lightmaps will perhaps be planned ?

Well great engine, just try to do a small game , to see how easy it is.
And using VB.Net or C#is as easy as XNA or even easier functions.

Try their tutorials.