Booner,
Disclaimer Upfront: I have only studied about and not installed Atmos in my HT.
That said; yes, you should notice a difference assuming the elements in the delivery chain support Atmos, i.e. Atmos content sent into an Atmos capable receiver.
The analogy I would offer is going from a 3.1 (L/C/R + sub) system to a 5.1 (as before + side surrounds) system is clearly noticeable (same assumption as stated above), even if you don't go the "whole enchilada" route of 7.1 system with back surrounds as well.
The most important factor in selecting 5.2.2 versus 5.2.4 is the room (size and shape) in conjunction with the seating position. I recommend taking a look at the
Dolby Atmos literature to help guide your decision.
- In a nutshell, the smaller the room or the less central the seating position the more likely a 5.2.2 will be the better (and cheaper) solution set.
If you provide room specifics, forum members can probably help more.
Cheers,
XEagleDriver