If you are using groups=2, then each filter will have 0.5*in_channels, as the operation is comparable to two separate convolutions using half of the input.
This also means that the number of parameters in the conv layer will be lowered.



 ttbb:

So the main question from my perspective is, if I loose some information when using groups=2 ?


The input will still be processes by one or the other group, so the convolution will still use the complete input information.
If you refer to the capacity (number of parameters) as information, then the grouped conv will have less capacity.