If you want to get the Sao Paulo for the skin, go ahead and get it. If you want it for the quad cannons, save your c-store points. I'll take my Mk 12 anti-borg weapons over those any day of the week, especially since they don't drain my engine power. Now, something to give the FX of quad cannons on my DHC weapons, well, that might be interesting.
The big thing about the quad cannons is that it gets you access to a high dps weapon at a captain level and is good up to at least RA UH 1 when you can replace it with a Mk XI weapons. Kinda like how I keep the weapons from the original enterprise so I don't have to keep replacing them.