Hey Danny,
Your cage looks to be 100cm at the moment, it is criminal that Pets@home get away with selling these for piggies unfortunately. 120cm cages such as the Ferplast 120cm is ideal for 2 piggies.
As for C&C 2x4 is the minimum for 2 piggies even if you have a loft.They take up less room than you think.
I personally love C&C and am a complete convert, we converted last year when we bonded Cookie with 2 friends. I don't see any cons to be honest at all. The pro's is more space for piggies and you have easy access to reach into them that you don't with traditional cages.
We have found that buying some PVC plastic picnic sheet from Dunhelm Mill and cutting it to fit the bottom of the cage, then putting a good layer of newspaper on top keeps the corex underneath protected and clean. Every cage clean just take the PVC plastic tablecloth out and spray it and make sure it is dry before putting it back.