I've now got a few more plays under my belt and adjusted my thoughts on Allied strategy accordingly.
I still think the French side is easier to play. They have the better army, with a larger stacking limit, a finer degree of articulation in units strengths (making it easier to achieve efficient odds and exchanges) and faster units. All these things make that side easier to handle. The speedy units, especially, make it possible for the French player to react to whatever strategy the Austro-Russians pursue.
The Austro-Russian allies do start with the initiative, and if they fail to keep it the French will eat their lunch.
There are three general strategies available to the Allies. My initial preference was to give up on the idea of winning by exiting units and concentrate on winning the attrition race to demoralization and seek out a decisive battle in the center of the map. With more experience I conclude that my aim was sound, but my means was deficient. It's certainly possible for the Allies to win such a battle, but against a clever French player the odds are not good. The French stacking advantage and speed will tend to result in unfavorable matchups in a main force confrontation. It's true that whichever side gets demoralized first will promptly lose, but on average it will be the Allies who suffer that fate.
A second approach that shows some promise is to try to pull the Allied army back in good order and exit off the East edge. Against a cautious or slow French player this can work. The threat of exiting most of the army may panic the French into attacking too hastily. If they do the Allies may have a chance to destroy enough French to demoralize them. Even if they don't, the Allies may be able to get enough off to win. The best French counter is a strong attack to demoralise the Austrians quickly, cut off their escape route off map and then mop up the survivors. Because there is a good counter strategy, however, it may not be as effective as the third choice. It's also likely to result something less than a decisive win for the Allies, if they win at all.
That involves making a serious effort to follow the historical Austro-Russian plan and attack on the left. The right flank Allied units and the small reinforcement group should stand on the defense at first and try to lure the French into committing a sizable force to that sector. If the French ignore them, move up. If they send too few troops over, kill them. If they send too many to fight, exit the map. The points probably won't count, but they won't count for the French, either.
Meanwhile, the Allied main body moves at top speed against the French right and the high-value exit area. They're not fast enough to make it off before the French get there, but the threat may induce the French to approach in a piecemeal fashion. If they do, then the Allies have set the stage for a winning attrition battle against just a portion of the French army. It's no sure thing, but it provides a good chance to demoralize the French. If demoralized, the surviving French will not be able to stop the Austrians from exiting enough to win a decisive victory.