OPA4170 : Full rail to rail input swing

Hi,

The part OPA4170 looks attractive interms of price and performance.

But, my application demands rail to rail input and output swing. In the datasheet of OPA4170, it is mentioned that the input swing will be 2V less than +ve supply rail during normal operation. Also, it is mentioned that it can be operated beyond this limit and very close to +ve supply rail(100mV) but there will be some degradation in performance. It is not clear that in what aspect the opamp performance degrades. 

Please mention those parameters(E:g: CMRR) which is affected by this rail to rail operation and by which amount it reduces.

Thanks,

Jebas.