It's also a bit strange that the filesizes are so drastically different. Did they really re-write the whole thing for a graphical change? Mac OSX 0.4.1 is 4.08MB and 0.5.1 is 13.8MB.
Windows version also doubled in size, yet the Linux version shrunk a little.
Qt apps are bloated, so that's not surprise for me. But the memory consumption are exactly the same or maybe a little bit less for Qt version.
No, Qt apps are not bloated: as he noted, the actual application got smaller. But Windows and Mac omit the standard Qt libraries, so Bitcoin-Qt includes them for convenience.
