Hi Ferenc,
I always found that SketchUp slowed to a crawl with any reasonable sized model, particularly if shadows are enabled. Are things better with SU 7?
Speed with shadows (and GI) is definitely an advantage of VBE which is under $300 for people on subscription ...and of course being able to 'walk' up stairs, and not through walls, etc... but you cannot beat free if SU is fast enough, especially since you can predefine saved view tabs for the client to navigate through the model.
Cheers,
Karl