I wouldn't take either offshore, but I would live aboard and learn on the bigger boat. I've only seen Pearson 30s, 35s and 39CCs, never a 323, but if it's like other Pearsons, it's a "middle-middle" boat in terms of build quality and sailing characteristics.
Catalina 30s are club racers and coastal cruisers. They have frighteningly large companionways that I wouldn't want to see take a wave. They are nice and responsive sailers, but I've seen them go squirrelly and get quite hard to control past 25 knots, because they are a little light and a little small in the rudder for heavy weather work.
There are a load of them around here, some very nicely fitted out, but I think they are a "summertime coastal cruiser", which is what most people want to do most of the time.
I think if you took either boat south, you would have to be very lucky or very good at picking your weather windows to avoid real trouble. You could drive a Miata across Mongolia, too, but the same logic would apply.
For one thing, neither boat has the tankage or the ground tackle stowage appropriate to distance cruising...200 feet of 3/8" chain on a Cat 30 might make it tip over...