Mixer : real 4 buses vs. Alt. 3-4

[jelly]

I'm planning to buy a mixer for my DAW. In combination with an audio interface card, maybe Delta/66 or Lexicon Core2, which both are 4 ins/4 outs.
I'd like to get 6 or 8 mono inputs for mixer. which I'm currently interesting in Behringer MX2004 and Spirit Folio F1. But the question come to my mind when I saw (2+2) instead of 4 on Behringer spec for subgroups. Well, it doesn't has real 4 buses but has Alt. 3-4 instead. What's the diffirence?
I'll use the mixer to record up to 6 or 8 ch. silmutaneously (ie. record drum set) and submix them to 4 ch. to my audio card. Will Alt. 3-4 do the job?

 

[Track Rat]

Yes

 

[jelly]

And how can I send out 4 seperate channel at a time?

 

[virtual.ray]

CH.1: Main out Left CH.2:Main out Right CH.3: Alt. Left CH.4: Alt. Right Cheers!

 

[jelly]

And what real 4 buses can do and Alt. 3/4 cant't?

 

[Track Rat]

A true 4 buss mixer would have 4 dedicated busses AND left/right mains outs. It would allow yo to make two stereo groups or 4 mono groups while maintaining your mains of the entire mix.