Ortleibs are proven performers on long expeditions. the mounting systems is strong and reliable.
Its nice to have waterproof panniers in the wet but the downside is that in hot, humid climates they can encourage mildew. Anything that goes in damp stays damp.
A touring bike is great as an all-purpose do anything machine. Tourers vary from full exp bikes (Bruce Gorden BLT) to fast, fun day-riding bikes . In the middle are club tourers that are good for either use (Trek 520).
The cx machines you are talking about are not racing cx but are modified for touring with all the brazeons etc.