There's only some limitations in swat 4 to have more then 6 players per map:
- Map's are small (can be avoided with playing custom maps as some are large in size and suspects)
- On tss switching to other teamcolor you can't see the other team's cam anymore to coordinate it (on vanilla this is not a problem)
- it really need to be players that actually behave or else it will have a mess on the map
Like always good tactical advice.