No, not really, natural hair brushes go limp when used with water based products, in my experience and as you suspect water does not wash out oil based finishes.
And concerning artificial brushes, different strokes for different fokes. I never use natural brissle brushes and I would be willing to compare finish results to what would be considered a good spray finish. Its all about knowing what you are doing. Contrairy to popular belief I get glass smooth with General Finishes oil based finishes and the recomended "foam brushes", a quality foam brush however, I use Wooster foam brushes.