We're using Domain Objects since couple of years without a problem (we have ~500 objects). Just pay attention that in some cases (like 1 in 100 or 1000) there might be a situation that your client would resolve the domain to IP address 1.2.3.4 while the CheckPoint GW would resolve that same domain to 1.3.4.2 IP address . To be honest, we never encountered that, or at leas I was not aware in those couple of years we're using it....
So in order not to face that, make sure that the DNS servers used by your clients, will be same as your CheckPoint Gateways, like some internal DNS servers....
One other thing, the object definition has an option to perform reverse DNS in order to assure that the IP resolves to the domain and vice-versa, still with cloud these days, the revers does not match.... so pay attention to that part.
Thank you,