On the surface, I'm not sure I want it. Armies aren't really armies if you can only have 1 or a couple units per tile.
What measure is an army?
A single stack, no matter how many units in it, doesn't really aspire awe until you hover the mouse over it. 100 units in a stack, impressive, but doesn't aspire awe like an army that takes several turns to land on a beach. But it also gives the defender an advantage. Look at Pusan in the screenshot. If it had been better developed, Pusan would've been a bloody battle since it would be harder to surround and so, starving the city would've been a viable option. After all, with 5UPT (the picture is misleading but my galleys, after promotions, only carry 4 units at a time), your options are limited in the case of Pusan.
For starters, I had to think about what units I was going to use. Do I use 4 Teutonic Swordsmen and ignore the defenses? Do I try to bombard the city with ships? Well, then I would have to build some ships to do the job but there's a limit on the number of ships on the tile as well and I needed triremes to escort....and so on in that case. Or do I land trebuchets on the island as well but in the process, limit the number of offensive units and make my job a little bit harder but a lot more satisfying?
And besides, playing with xUPT against other humans opens up both player's options immensely.
There's also the case of this:
Long story short: Continent is divided between Siam and Germany and naturally, the border ended up being a little to the west of the small lake in the middle of the map. I wanted to invade Siam but it took
several turns for me to get the force I needed through that mess. The surrounded city in the top-middle left of that picture only had enough room for 18 units (at 6UPT) and since it was coastal, it was resupplied more often than I liked.
And then there's that Pop 8 city with all the German troops starting to surround it. Slowly and surely, things became desperate for that city. It wasn't coastal so it couldn't be resupplied with troops easily and new troops were auto-kicked out. I was constantly bombarded by longbows in the city. As you can tell by the picture, the military strength (shown by how dark the tile is) of that city was larger than the tiles surrounding the city containing my troops. In short, it took 'bout 20, 25 turns to get to the point where I had both cities compared with the, oh, four or five it would've taken with 20-unit stacks.
I had 'bout 48 units on the border (maximum) and it looked vastly more impressive than simply 1 stack of 50 units.