Supported forms for mount paths are:

Normal single-host (these are unchanged)
<path> host:/path/path

Multiple replicated hosts, same path:
<path> host1,host2,hostn:/path/path

This will do an initial RPC call with a .1 second timeout to all hosts to 
find best match.  If this fails, it will try a 10 second timeout, if this 
fails it takes the first host.

Multiple hosts, some with same path, some with another
<path> host1,host2:/blah host3:/some/other/path

Works as expected

Multiple replicated hosts, different (potentially) paths:
<path> host1:/path/pathA host2:/path/pathB

Same as above with RPC calls..

Mutliple weighted, replicated hosts same path:

<path> host1(5),host2(6),host3(1):/path/path

Will pick lowest weighted host that responds to RPC call.  
RPC time is not counted, only whether the call got a reply 
at all.  Initially does a .1 second timeout, if all hosts 
fail this, moves to 10 second timeout.  If one of the hosts
is localhost, the automounter will choose that regardless of
its weight.  (This has been done to remain compatible with
Sun's automounter)

Multiple weighted, replicated hosts different (potentially) 
paths:
<path> host1(3):/path/pathA host2(5):/path/pathB

Same as above with RPC calls/weighting.

Anything else is questionable and unsupported, but these 
variations will also work:
<path> host1(3),host:/blah

Unsupported and I don't know why you would use this, but will 
work.  Weighted host always gets precedence if it responds to RPC

Anything else, I ain't making no promises.

Jason