How do they stact vis-a-vis direct sale on website.

During the course of this study I reached these websites:
[offering just trial offer]
and
[offering both buy now and trial offering]

Which one would be better?

Is there a study to compare the two media's.

[edited by: coopster at 5:17 pm (utc) on Feb. 26, 2009]
[edit reason] no urls please TOS [webmasterworld.com] [/edit]