Perhaps no one has answered you yet.
Short answer is 'they should be fine.'
I installed a set, not from BD, so can't comment on theirs, but ones I put
in were 400 dollars for the set - at that they BETTER work for a long time !
I opted for the two part set up, rather than two very long pipes, I got the
set that's two half length pipes for each main pipe.  Worked just fine.

Besides, what else are you going to do anyway ..............choices are  - -
use the old plastic pipes, new plastic pipes, metal vanagon pipes, ( which
is going backwards ) , or copper pipes you make yourself, and copper really
isn't right, or long heavy duty marine hose, which is expensive, heavy, and
deteriorates faster that metal probably. 
  They should last just fine, the stainless ones, and so would painted- on
-the-outside- plain-ole metal pipes if people changed the coolant like they
should, or even exhaust pipe, as long as you protect it from corrosion on
the outside and inside.
Scott

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
Jeff Clayman
Sent: Saturday, February 09, 2008 7:45 AM
To: vanagon@GERRY.VANAGON.COM
Subject: Bus Depot Stainless Coolant pipes

I have an 87 a/t van with the long platic hoses.  I am going to lobotomize
my cooling system and replace everything.  Are these hose worth replacing
with the stainless ones?  Have these ever failed on anyone?

Jeff