Using Sun 3 and Sun 4 machines together

[Dale Call]

My group has a network of Sun 3/60 workstations running Sun OS 4.0.1.
With Sun's recent product announcements, the Sun SPARCStation looks like
the product of choice.  So what I need to know is how well do Sun 3's and
Sun 4's plug and play (act as file and yp servers to one another, talk to
Vaxen running BSD and Ultrix, etc.).  I'm also interested in what folks
have to say about porting applications from Sun 3 to Sun 4 (our
applications have already been ported from Vaxen to Sun 3, so I hope some
porting issues were resolved then).

Finally, if anyone is running the GreenHills C cross compiler for 680X0 on
a Sun 4, I'd like to hear about your experiences with it.

Any information appreciated,

Dale Call
dcall at amadeus.la.tek.com