No, it’s not true - not unless there is some unusual molecular structure to Australian water that allows it to infiltrate coatings that are quite waterproof in North America. I mean, Sierra Designs says their tent floors are capable of keeping water out at a pressure of 165 pound per square inch. So you’d have to be camping on a pool of water, then jumping up and down on the floor repeatedly to drive any water through. Really, both the Tiros AST ($425 U.S.) and slightly larger Stretch Dome AST ($469) are first-rate tents - four-season stalwarts.
As for continuous pole sleeves, tents today come with either pole clips (which Sierra Designs favors), full-length sleeves, or a combination of the two. In what is something of a hair-splitting exercise, the general consensus is that sleeves result in a sturdier tent by virtue of their continuos connection with the canopy, while clips promote ventilation by creating a free-air space between the canopy and fly. In reality, in most conditions one can imagine, the practical difference is slight. MSR, for instance, uses continuous sleeves in its Fusion 3 Convertible ($359). One meaningful difference between it and the Sierra Designs tents is its use of a polyester fly (SD uses nylon taffeta). Polyester is generally said to be more UV-resistant than nylon, and it stretches less when wet. MSR also has upgraded the tent floors from the material used by Walrus, its predecessor, for wateproofness that should be on par with Sierra Designs, if not better.