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.

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