Cons of an ITX Motherboard

[adampcpower]

This is a pretty easy question that I cannot find the definitive answer to. What are the downfalls, if any, of an ITX form factor motherboard OTHER than less slots for components. Is there any performance issue with smaller boards or anything else? The reason i ask this is because I am moving to a smaller location, and downsizing my gaming pc from the Antec 1100 case i have with an ATX ASRock z77 extreme4 mobo in it would be ideal, but i dont want to compromise performance to have it a bit smaller.
If someone could explain this to me and/or recommend some great gaming ITX board (if thats even a thing) that would be great.

Current System:
CASE: Antec 1100
CPU: i5-3570k
CPU HEATSINK: Coolermaster Hyper 212 EVO
MOBO: ASRock z77 Extreme4
GPU: ZOTAC GTX 670 AMP! Edition
RAM: G.SKILL 8gb (4x4gb) RAM
HDD: Seagate Barracuda 1tb 7200rpm 6mb
SSD: 128 gb Vertex 4
PSU: OCZ FATAL1TY 750W

 

[IntelEnthusiast]

The cons of ITX is also the pros... Its small size. This allows it to be easy to move around but it doesnt allow a lot of expansion. Because of its small size ITX may have 1 or at the most 2 expansion slots.

Oh dont forget to take advantage of the promo on the Intel® Core™ i5-3570K at http://www.intelgamingpromo.com/intel/wintergiveaway/register

 

[adampcpower]

So there is no performance difference between the two? even if im using it with a high end graphics card for gaming?