Imagine one is not 100% sure regarding number of hosts and behavior and growth of multicast applications in the network.
Some folks on my team believe that configuring 'sparse-mode' is appropriate. If I am unsure, is there any issue or problem if I configure on my router interfaces 'ip pim sparse-dense-mode'? I mean, why not deploy always ip pim sparse-dense-mode instead of sparse-mode since the former would cover both dense and sparse?
It depends on bandwidth usage on your network. As you know,dense mode always flood/prune multicast packets on your network. Sparse mode will send multicast packets when someone asks for. In case you have a few receiver on your network it would be sparse mode for that. As per your question "ip pim sparse-dense-mode" is a good command as you mentioned. It will use dense mode for group that doesn't know about the RP. For sparse mode 18.104.22.168 and 22.214.171.124 are still flooded as dense. So if you use an "ip pim sparse-dense-mode" command it would be fine. You can also use "ip pim sparse-mode" and "ip pim autorp-listener" to get rid of that problem.