Hi,
I have both the C2 Duo (two years) and the CS (two weeks), both with RMRcc RDSs. I've got just under 5,000 rounds on the C2 without a single issue! I've got 400 rounds through the CS, again without any issues. On paper, they are both similar in size and weight. However, after putting 100 rounds through the CS and then going to the C2, the latter feels like a brick. Not a "bad brick", but just bigger and heavier. The recoil impulse is only modestly greater with the CS over the C2. Also, I've had the grip reduction on the C2, so it's not just the grip size.
For CCW, I'd strongly vote for the CS, which I carry in either a Crossbreed IWB or a Blackpoint OWB (same holsters I've used with the C2). For occasional CCW, range or home defense, I'd recommend the C2. I will probably send the C2 off to Staccato to have a threaded barrel fitted to make it a host for my suppressor.