The grip connector is the same in both bases (MongoosT-50 and WarBRD).
If you want to use extensions, then get the MongoosT-50 base.
WarBRD base should not be used with extensions. And, unlike the MongoosT-50 base, WarBRD base can be used on a desktop. But also can still be installed on a mount.
One is not replacing the other. They are designed for different use scenarios.