[Test-Equipment] Vector network analyzer choice

[Larry Aamodt]

Greetings

I'm looking for wisdom from those on this list who may 
have experience with HP/Agilent vector network analyzers.  More
specifically, if one were to choose a purchase between these
models, which would you choose and for what reason?  I realize
that the first couple models are discontinued and that the
last one has greater bandwidth (6GHz is adequate for our needs).
I also recognize that price could play a part in choice, but I
am interested in technical merits, reliability, longevity,
maintainability, etc.  I believe all models below have the
functionality we need.  This is a significant investment and 
I want to make the best choice. 

Here are representative models:
     8753D with opt. 6 (6GHz)
     8753E with opt. 6
     8753ES
     E5071B
 
Thank you.

Larry Aamodt
Professor of Engineering
Walla Walla College
aamola at wwc.edu