Issues calling spamc via pipe?

[Jason Lixfeld <ja...@lixfeld.ca>]

I was browsing some stuff and I think I read something about it being 
bad practice to run SA like so:

begin routers
spam_check:
   transport = spam_kill
   ...
   ...
   ...
   ...

begin transports
spam_kill:
   driver = pipe
   command =  /usr/local/sbin/exim -oMr spamassassin-scanned -bS
   transport_filter = /usr/local/bin/spamc -d 127.0.0.1 -u $local_part
   ...
   ...
   ...
   ...

I can't find the link anymore and I'm not sure if what I read is 
accurate or not...  I think the comment was something along the lines 
of "...piping stuff is a kludge for lack of a proper way to do it..."

Is it bad to call spamc from a pipe or is this normal practice?