I'm against respawns.. Even in waves as this could quickly result in spawnrapes, or chaos at spawn. (Which is not that interesting)
(Again, look at singleplayer where this happens all the time. Kill off first wave, then set up xbowmen/archers in crossfire right outside their spawn)
Also the respawn system creates this constant stream of fresh troops that nullifies encirclement etc.. It basically takes out most of the tactics, no matter how you look at it.
Better then to have series of battles on the same map. It opens up for so many choices. Commander could tell part of the army to become hoplites next round, then maulers the next etc.. Both tactics and troop composition would be dynamic. A good team of players could loose to a commander who got his troop composition right i.ex, or had simply a better mix prepared, compared to a commander with more money, but a more rigid composition.
But most importantly.. solve the lag issues! I cannot fathom why it still exists. If one could fix that, then I see us having 200 player battles in series.
Take the stupidity out of strat battles.. We all crave it