Well my 2 cents is that cross training. (striking or grappling) is a great addition to your Aikido, but first you have to be fully grunded in Aikido. That means that you have trained long enough so that to some extent the Aikido is now natural to you and you understand not only how to do specific techniques but also the principals of Aikido. I train in Xing Yi as well as Aikido and I have found it very to be valuable, but my home art is Aikido and I bring the Xing Yi into it to augment and explore. You didn't say how long you have been training in Aikido, but my sense was not that long. Again, I think to really get value out of the cross training you really need to make sure you are grounded in the Aikido first. Again, just my 2 cents
That's the conventional wisdom, but I wonder if it's really true.
We don't tell kids in Little League not to play football because it might mess up their baseball if they don't have a firm grounding in it.
They might be advised not to to both at the same time, but that's more a matter of allocation of resources than anything else.
Aside from the time restraints - it hasn't been my experience that it's any problem at all.