I have a 402 PCC. Its slightly smaller than the 401 PCC, only holds 402/403 batts. Since switching to 16340 battery MODs, I no longer take the 40x stuff with me when I'm out and about. All the same here's what I found with PCCs...
* they can be fiddly and too frequently refuse to charge a battery
* while roughly the size of a pack of cigarettes (slightly larger really), they are rigid and do not fit as comfortably in a pocket, also they don't get more compressable as a pack of smokes does as you smoke'em down
* they take longer to charge a batt than a normal USB charger does
* they don't charge as fully as a normal USB charger does
* they don't actually hold that much stuff for their size
When carrying std ecigs, I had better luck with a "soft-pack" of sorts that had no charging capability. Instead of bringing a PCC that could charge 3 to 5 times, I would bring several fully charge batts with me in the "soft-pack". It was smaller than the PCC and more comfortable to carry and more flexible about what you carried in it (perhaps different sizes/models or a 3ml dropper bottle instead of some prefilled carts).
Now I'm using the same "soft-pack" to carry my 16340 MOD plus a spare battery and a small dropper bottle.
I got this at REI one day not too long after trying a 510 model and having no convenient way to carry it in my 402 PCC. Been using it ever since as my e-cig pack regardless of what type of e-cigs I'm using that day,
Keychains - Keychain Pouch | Marsupial Wallet Key Chain | Chums
The 401 is slightly longer than the wallet ('bout 1/4 inch longer, fits fine in the outer pocket). The 402 is slightly shorter, the 403 comes just to the top of the outer pocket. If you replace the keyring with a S-Biner, it can be clipped it to a belt loop (which is generally what I do with it). Otherwise, its a very small very pocketable wallet.
Mine doesn't have flowers on it thou