We have a 323 which we have owned for eight years. Like the 321, its somewhat tender, but once it's trimmed it sails flat and fast. The main thing to remember is to reef sooner rather than later. Our boat has the conventional main and slab reefing. It's a simple process to reef and can be done from the cockpit. We bought the boat because it's lighter overall weight would presumably help the boat to sail faster in lighter air.
Another consideration was that the boat was purchased as a day sailer, we don't cruise with it. If I were to cruise, I would consider a heavier boat, but overall this boat suits my situation at this time.
I bought the conventional rig because of the increased mainsail area over the furling main, and because I have seen too many issues, and heard about more with in mast furlers failing to operate properly at most inopportune times. Presently, you couldn't pay me to buy a boat with an in mast furler. That is obviously my choice, and I have sailing friends who would readily disagree. One has to make their own choice based upon sailing conditions and intended use..