Here is an excerpt from my own build thread on the HobbyCNC vs. the G540. I wrote this less then an hour ago, so I guess the timing is good. Hope it helps! I am selling my HobbyCNC board, but I would give it the same review if I was not. It really has been great. PM if your interested.
A few words about the HobbyCNC EZ board. It was great. It required a bit more setup work then the G540, but in the end it did it's job quite well. Where it clearly does not have the same holding power as the Gecko Drive, it was plenty for a table this size. I would be comfortable using it again. When making signs, and plastic parts the power was sufficient. When cutting hardwoods (up to 2 inches thick) with a 1/2 end mill it was sufficient. Even cutting Mic6 aluminum was no problem for it.
Thats not to say the G540 is not an improvement on that- it is.
I did some price comparison:
HobbyCNC EZ Kit comes with 3 steppers, wire, and most of the components for the power supply. All you need in addition is a box to put it in, and a transformer.
$290 - HobbyCNC EZ kit
$45 - 12A transformer.
$20 - Enclosure
$45 - Radio shack connectors
$400 total cost
The Gecko solution is a bit more simple - just the G540 and power supply. No assembly needed. You still need to solder your DB-9 connectors.
$300 - G540
$160 - Power Supply (12.5A in my case)
$45 - Connectors
$150 (3x budget steppers)
$655 total cost
An enclosure is a bit more necessary with the HobbyCNC solution as the power supply has a lot of components. You could also use a regulated power supply, of course. It was just cost a bit more.
Anyways, hope thats helpful to anyone wondering what they need. Both solutions work great. The HobbyCNC is a great way to get started, plenty of power for smaller machines, and great value. The G540 offers a bit more power, is a bit more simple to get started, and has fewer components to worry about.