I haven't had a chance to do an in-depth comparison on the orbats to find all the small tweaks in points and stats, but looking at the new battle groups, I love the idea. It adds some nice elements of structure to list building. Actually, it strikes me as a similar approach to the Helixes used in Planetfall.
The only downside is that the main perk seems to be getting a free TAC card and not handing over victory points for using it...this assumes of course that TAC cards are being used. For those players that prefer to play without them, these groups don't have much draw to them.