I dont think smaller map would work. A 256x256 map is 10 sectors and a bit square. A 128x128 would be 5 sectors and a bit square, and 64x64 would be 2 and a half sector square.
So a 64x64 WOULD be making a DA.
A 128x128 would be 25 sectors for 3 countries, 8 sectors each, 2 sectors water, 6 sectors land, rule of thumb is one base per sector, need 30% for war win which means capture 3-4 bases (adding in V bases) per side to win the war. Reset in an hour. Not to mention how close strats would be, bombers would never get over 5K because they would be jumped almost as soon as they took off.
Smaller than 256x256 wouldnt work in the MA. Again, I think its the size of the fronts. Using water and mountains to keep the fronts no wider than a few grids would funnel the fights. Less places to run off and play hide and seek to avoid the enemy. It could work on the larger maps as well, but the lay outs would look really odd.