PSN is great 'cause you can have as many accounts as you want
That's only half true. The PS3 is limited to 16 accounts.
So if you want to create more than that, you'd need to delete some from your current console or buy a new PS3.
I stand corrected, but still...
It's still cheaper than getting 16 xbox live gold accounts. Even if you bought an extra PS3.
A $300 PS3 vs an xbox 360 with $50 per year gold accounts... 6 gold accounts and you're over the cost of a second PS3 which would put you at 32 PSN accounts and 6 xbox live gold account for roughly the same price. Not counting the first consoles of course. Also not counting that xbox live is "Per year" and the PS3 is a one-time cost.

Then there's the flip side of "Who the heck would even need 16 accounts anyway?" If it was for FC2 map slots that would be 320 maps.

I don't think we've even made that many between all of us on Cdeezgames.
But think about it, if you delete an account off your PS3, I don't think it deletes the account from PSN so... Fill up your 20 map slots, make sure they don't need updating, delete account, move on to next 20 maps, rinse - repeat - etc... LOL