I wouldn't call myself a Marcionist, but it does sound like we agree on some points.
I certainly have no link to Gnosticism nor would I set about to purge any influences, of whatever origin, out of the scriptures.
I do feel that Christians should try all of the scriptures using the words of Christ as the absolute uncompromised standard.
Whatever disagrees with Christ should be considered fit for use only as a "dandy bad example" of tripped-off theology, but certainly not for use as doctrine to live by.