I have a 1.25Ghz Sonnet G4 with 2MB cache in a 2001 Quicksilver, got it because the last owner could not get it working correctly (hardware software issues). I use that machine for my main Mac currently it has a new 22X DVD-DL burner, max RAM, a USB 2.0/firewire card, and an ATI 9000 video card booting OS 9.22 and OSX 10.4.x on seperate HDs. The benchmarks are about 2x what my 2002 Quicksilver G4-800 (no cache model) gets. I assume your G4-733 is from a 2001 Quicksilver that also has no cache, hard to even give those away.
While I love the Sonnet upgrade I can't see spending $100+ for it when you can get a Mirror Drive Door dual 1Ghz cheap these days. I paid something like $35 shipped for mine because of the software problem (machine plus CPU installed). Sooner or later I will find a cheap Dual G4-800 or 1000 with cache for my other Quicksilver to speed it up, but only when it is cheap. With the X86 only OSX versions out you will find people dumping anything G5 and earlier for peanuts, so waiting a bit might be a good idea unless this is your main machine (I use X86 PCs for my main machines).
While I love the Sonnet upgrade I can't see spending $100+ for it when you can get a Mirror Drive Door dual 1Ghz cheap these days. I paid something like $35 shipped for mine because of the software problem (machine plus CPU installed). Sooner or later I will find a cheap Dual G4-800 or 1000 with cache for my other Quicksilver to speed it up, but only when it is cheap. With the X86 only OSX versions out you will find people dumping anything G5 and earlier for peanuts, so waiting a bit might be a good idea unless this is your main machine (I use X86 PCs for my main machines).