Analysing SQL Server Network I/O
Your correct, 2008R2 and onwards has the *_rows added to sys.dm_exec_query_stats. I would say that's the way to go.

You'll have plenty of queries that can create massive disk IO but still have a small result set. However, it's not possible to have a huge result set without huge logical IOs.

So look at query stats ordered by logical io's first, then row count second. That will give you a pretty good starting point. 

Before 2008 R2 I would look at which queries with large logical IOs have network related waitstats. The problem with this approach is. 1) Once the network is saturated, it's likely that not only your large queries, but pretty much all your queries will have network related waitstats. 2)Network related wait stats are in many cases not caused by network related issues ;-)

cheers,
Edward