I have tested 'view as icon' by sending email attachment to myself, and altho it shows as an icon in the email I am composing, pdfs & jpegs appear as "view in place" in the recipients mail. (MSOffice appears as icons).
My concern is that many recipients don't know that the images in their emails are attachments and can or supposed to be saved to their computerfor other use.
Horror of Horrors, not everyone I communicate with has Mac or uses MacMail.
Interestingly, when composing, jpeg and png (maybe other formats too) attachents can be adjusted to "small-medium-large-actual size in a small drop down menu to right, just above the message composing area, but this will also change the the dpi of the received jpeg ( Size of 300 dpi jpeg sent at "small" is received at 72 dpi)