It looks like the SDC for me, as Harb said it can be packed up behind your back seat for those rare moments when you need to have a quick swing. With the GT only around 3 hours away, my weekends and days off can be limited. So maybe swinging the SDC for the smaller stuff will eventually pay for a GPX. A mate lent me his ATX a few weeks back which I took to Dunolly, came across a small quartz reef in my walks which ran down into an old creek, after twenty minutes swinging the ATX across the sides of the gully, with a harness and bungee I was totally buggered, swinging this so called "portable" No offence to him or Garrett owners but why would they build such a portable monstrosity! I felt and gave a bit of a swing of an SDC just a couple of days ago, wow what a difference, like swinging a cat by the back legs rather than a cow and packs down next to nothing. This fellow did say the SDC has or had troubles with the batteries sliding in and making contact and some thing about a hinge..which he fixed other than that he wouldn't part with it. he also has the 4500 which he uses first then goes back over with the SDC.
Looks like I'll keep my eyes open for the "unwanted Christmas Gifts" at the end of January
Mick