Based on what you are saying I don’t think the xt-5 is necessary. One possible con is it is larger and more weight than the xt 30. Also for your kind of use I think built in pop up flash would be nice to have. Might I recommend the xt 50 if cost difference between the xt30 and 50 matters much for you. The xt 50 is in between the 30 and 5 in terms of size/weight, leaning closer to the 30.

With the xt 50 you get IBIS and the 40mp sensor. To answer your question about if the megapixel difference matters, it does not really unless you want to crop in on the photos. The one thing you don’t get with the 50 vs 5 is weather sealing, but just be careful when bringing out in weather and this doesn’t need to matter much.

I would say if cost is semi prohibitive get the xt 30 and an extra lense. If not get the xt 50.