RoN has multiple strategies, length of play and micromanagement options. Sadly, I've been told that the PC version has been discontinued for sale in Australia -- it has been really hard to find in mainstream outlets. BigHugeGames -- the developer -- have just purchased an advanced software package for their next project. (We could pray that, now they've done CivRTS via RoN, they'll do their own version of SMAC II, given Brian Reynold's role as the SMAC developer and Tim Train's role in bringing us SMAX).
[OT: Has anyone played both C&C: Generals and SWGB? I'd be interested to read comparisons].
We may eventually see RoN, particularly if the port is advanced at Westlake (?). Pity MacSoft have gone quiet recently, probably deluged with Halo sales.
EDIT, added: If MacSoft are listening, I think that I'd really get more value from Civ3 Conquests. Civ3 continues to be the most-used game on my Mac and there are some really marvellous additions made possible via Conquests. I am a single-player versus the AI user and Civ3 provides me with the most satisfying gaming experience. I just want the novelty of adding new bits every-so-often.