after more experimentation with 3.2.1 on my DXG i've discovered a good work around to the slow wake issue....
1. disable the screensaver via ;debugOn ~disableScreensaver
[this never used to work on DXG or Kindle 2 but does under 3.2.1]
2. manually power off by holding the power slider for 5 seconds...kindle will go blank
3. flick the slider to power on again...my kindle then comes to life after only 4 seconds!
as well as avoiding the slow wake ups, this setup gives me the advantage of having my kindle on all day when i need it without those annoying screensaver timeouts (i was using a hack to delay them anyway). i seldom have 3g on so battery drain is minimal. if i know i wont be using it for a few hours i just power it down fully.