In MP there is quite a bit of Merc stealing. I purposfully will kill off a merc company if I don't plan on using it so it's valueless. Or if I have a feeling they are going to try to outbid part of an army romping through their territory.

There is quite a bit of strategy when dealing with mercs in MP as opposed to SP. I would hope that in the near future they make more merc companies availiable in a staggered fashion, and of course fixed some of the irritations (like auto-bidding if you have them, or maybe a reminder the turn they are looking for more cash. Autoset at the 'half' price if you already own them etc)